I'm not sure if there is an actual transfer available. I just gradually accreted passwords into Keychain by having LastPass on normally, and then accepting the prompt when Safari asked me to save the password.

iCloud passwords works with Chrome and Edge on Windows but generally yeah you need to be all-in on Safari :V

There’s a csv import and export, it’s supposed to be compatible with things like 1password, chrome and a few others.

I didn't know that was available (I don't think it was last time I checked). Thanks, worked quite well with the exception of a bunch of conflicts it wouldn't import.