nocturne

skip to 1:45 for actual instructions, or watch the whole thing

But step 2 is put your junk in the hole.

Would any of this be hard or impossible to replicate in proton mail?

AFAIK you can keep using the forwards to Proton, but in the free version you are unable to reply from them. I have unlimited and I have several addresses set up this way but I am unsure of the limit.

Yes. It has been a while since I moved (whenever the first breach was), but I exported from lastpass and imported to Bitwarden with minimal issue, I think I had to add a column.