With respect to James’s original questions, I think they were answered in this interesting discussion by Dr Mark Kidger from 2020:
https://www.youtube.com/watch?v=yYK-28E8c0A
What struck me was his assertion that Betelgeuse will be a point of light that is as bright as the full Moon, and it will not be possible to safely look at it with the naked eye, let alone any other instrument, without heavy filtering.