According to believers in the inexorable damnation of the unreached, how is God not unfair for letting someone be born in unreachable conditions?

A view that hasn't been addressed by any answer so far:

There are in a sense two aspects to the scenario; firstly, that the person in question was born when and where they were, and secondly that the Gospel has not reached that time and place.

As to the first, the person's lack of control over the circumstances of their birth. It may be unfair, but not on the part of God, because while it is not the person's fault that they are born in the time/place/circumstances they are, nor is it God's. Rather, it is the result of a long chain of what were ultimately human decisions, from that person's ancestors' decision to settle in that location, to their parents' decision to procreate. Did God know this would happen? Absolutely. Was it part of his plan? Absolutely. But was it also ultimately the result of human decision and action rather than God's? Also absolutely.

As to the second, the absence of the Gospel when/where they were raised, this is again ultimately the result of human decisions/actions. In this instance, it is the failure of Christians to reach these people, as well as the decisions of those people and their ancestors that resulted in their hard-to-reach location. The bible makes it clear in several places that it is our responsibility as Christians to spread the Gospel to those who have not heard it. For example in Romans 10:14-15a, "How then will they call on him in whom they have not believed? Ans how are they to believe in him of whom they have never heard? And how are they to hear without someone preaching? And how are they to preach unless they are sent?". Thus, the absence of the Gospel in any area is not God's failure, but ours, which I think gives more weight to the duty of evangelism and mission work than many believe.

Personally, I do not believe that it is possible for the unreached to be saved without explicit knowledge of the Gospel, for scriptural reasons and the fact that people are not raised in a vacuum with nature; the combination of our corrupt natures and traditions that are inevitably passed down in any culture, I believe, prevent anyone from being saved even if the general revelation of nature were sufficient.

EDIT

One aspect of the question I did not explicitly lay out was whether God giving said person life, knowing their fate, is cruel or unfair, as opposed to the child being stillborn or a 'philosophical zombie'. I'm inclined to think that, as an extension of giving humanity free will, He has allowed us autonomy to have children when/where we will. Just as free will results in sin yet is still permitted, so does deciding when to have children result in children born who will never be saved. The argument for this being unfair seems to rest on the unreached nature of the circumstances they are born into, which I believe I have demonstrated is the result of man's actions, not God's. I do not believe we are in a position to say whether it would have been better for creation as a whole if God had prevented that child from being born.

I'm just going to assume this question is on-topic and answer accordingly. This results in assuming certain other things to be a certain way because changing them renders the question off-topic.

Thus, point 1: A person is only called to answer to what he knows. This has actually been debated through the ages as to whether or not it is true; with some rather famously arguing the passage "will be beaten with but a few" being the relevant teaching here. Yet others argue "I will go to him; he will not return to me" and some others.

But you yourself gave point 2: "dream". I am three steps from the front and have the direct testimony of this being the tool used by God when no others will suffice.

Know this, for we have seen it. As soon as one makes the first step God is willing to move heaven and earth that he shall not be lost. As the eunuch on the road to Ethiopia is the example, God shall act by his mighty hand. See that God picked up Phillip and put where he needed to be to save the Eunuch. I have other records that you may or may not believe; but this is the answer.

Here is a partial citation. You will notice on reading it that it's missing information that would let you confirm it. This is intentional. https://www.thegospelcoalition.org/article/muslims-dream-jesus/ It is well matched to what I already know.

A question has been asked by OP to gather the stories of the pagans calling out to God and receiving an answer before any humans reached them. It is not for these stories that I believe it yet if I were to curate these I would find some true and defensible. But it is by the record I have received from Muslim countries that I truly believe this is the answer.

I am sorry, but I found that those who hold no salvation for the unreachable tend to avoid the question. I have heard it said that no such will be born who cannot be reached but would otherwise be saved, but the best evidence I have says that just isn't true. I have also heard it said that you cannot call Him unless he is calling you, but that to me is evasion and not an answer at all.

For all have sinned.... The first part of the answer is that in the absence of Christ's death on the cross, justice demands that all humanity suffer eternal torment because of our sins. Thus fairness would be universal damnation. So the salvation of even one person is not fair, it is grace. This point is driven home by Paul in Romans.

This article discusses the idea (supported by Jonathan Edwards and others) that finite sins against an infinitely holy God are infinite sins:

https://rethinkinghell.com/2016/05/28/what-are-we-to-make-of-finite-sins-against-an-infinite-god/

Everyone who calls... The core Gospel message has remained unchanged since the time of Enosh in Genesis 4: At that time people began to call on the name of the Lord. Paul tells us what that does:

11 As Scripture says, “Anyone who believes in him will never be put to shame.” 12 For there is no difference between Jew and Gentile—the same Lord is Lord of all and richly blesses all who call on him, 13 for, “Everyone who calls on the name of the Lord will be saved.” (Romans 10:11-13)

So in Genesis 4, people began to call on the name of the Lord, and Paul tells us that everyone who calls on his name will be saved.

But to whom does that name refer? This is the problem. It is possible to get the name wrong, meaning calling on a God whose character is wicked. This is where "reached" versus "unreached" comes in. How can you (as Paul also says) call on one of whom you have never heard?

Job. Job is God's counter-example for all who challenge his justice. Job was not Jewish. He likely lived in the time between Abraham and Moses. Job was in deep distress. He took stock of all his troubles and made up a "job description" for a savior. Then he cried out to God to send such a person to save him. After a careful study of Job, I discovered that the mediator Job sought to square things between him and God had to satisfy nine qualifications. Those nine qualifications correspond to nine events in the life, minstry, death and resurrection of Christ - and appear in Job in chronological order. So basically, Job, a seeker after God, figured out what the gospel would have to be to completely rescue him - and God then showed up and told him that he got it right.

Thus a righteous person who conscientiously pursues God will be granted insight into the gospel by means mysterious to us.