That sounds reasonable, though "related" is maybe an awkward phrase, in that the Meta-Crisis Doctor, for example, is definitely "related" to one of the "widely-accepted" Doctors, just not as a straightforward regeneration of him.
But again, if we're playing that game, the Timeless Children are from being "confirmed outright" to be directly related to the Doctor. Even if we taken the Master at his word (and again, this seems like a very odd thing to do), there is also User:TheOneTrueJack's point that we don't know by what mechanism the last incarnation of the endlessly-regenerating Timeless Child was turned back into an amnesiac First Doctor. If it turns out to be a mechanism comparable to how the Other turned into the First Doctor, what then?