I can see that I didn't give enough information, as lots of people are suggesting 1Password, which I use already. I want to be able to sync 1P with GA, but it's not possible despite lots of people asking the question.

Looking at all the options, it's clear to me, with too many 2FAs set up already, that the only practical answer is to continue to use the phone for existing accounts, and maybe start trying something else for new ones, but probably not.