TomClark posted... That could work, tbf.
I lean more towards 6B since it semi-officially confirms there was already has a period where The Doctor is somewhat unwillingly doing covert operations for The Time Lords with his memory of these times probably removed afterwards, so the setup itself is already there, while The Master mentioning in TPOTD that the Time Lords forced a regeneration on The Doctor more than just when Two became Three felt very much like a "so if you want to believe Troughton became Martin became Pertwee then this is the line you can use to support that, whatever, it's my last episode, do what you want" moment from Chibnall, haha.
You know what, I wouldn't mind if that was the true timeline of events and the Timeless Child was just the Master fucking with the Doctor's head again.