The problem with her just being a pre-Hartnell a la Morbius is that 1) the rumour is that they're going to say all the first set of Doctors were 13 women, and go for gender parity in throwaway dialogue in spite of the Morbius Doctors being all beardy blokes; 2) the TARDIS isn't a Police Box until Hartnell; 3) if they're Morbius type pre-Hartnell Doctors why doesn't she remember having an earlier cycle, given that she's seen and remembered several of them well enough to project them on a screen in her fourth incarnation... And so on. It still doesn't work.
Now, if by "nuked" the Master meant "went back and invented Gallifrey from scratch but it all went a bit squiffy" that would be an appropriate out for how we ended up with a different First Doctor.
Maybe it’s the season 6B Doctor, they give a new cycle, kill two doctors, and wipe the memory in time for Pertwee to fall out the door and it still add up to thirteen for Capaldi. This of course makes no sense.
And of course, the Ruth Doctor cannot now remember any of what happened, because that’s how crossing your timeline works.
And of course, the Ruth Doctor is actually a five year old girl, because she has to have aged up to the time differential on meeting her later self. But that didn’t happen.
And all of this happens without Gallifrey ever knowing, no Time Lord can ever know, because then that information would be in the Matrix, and the Lord President would have known it...like the Doctor was about three times. (Which is why the Masters big secret better be amazeballs.)
Also, this is all on contemporary earth, so how many Tardis have been stuck there at various points? It’s a wonder the Doctor knows where they have parked.
Oh.
And Gallifreyan Mean Time, The Doctor has just revealed the future to past Gallifreyans, no mention of a mind wipe (Gat didn’t regenerate and is therefore back in the matrix, or wasn’t a Time Lord.) or any ramifications.
There’s gonna be a mass of contradictions, or a mass of walking back, and well...
They still wasted the first BAME Doctor on a flipping gimmick.