This is (hopefully) a problem that platform owners can solve for us, and if they do I'll love them for it, but they very likely won't take it on.
Apple/Google/Microsoft can bake in cross-device syncing into the browser/OS and apply this sort of thing on form auto-fill.
It'll break down when:
a) Hashes don't meet site-specific password requirements (too long, missing special characters, etc.)
b) Sites store passwords in plaintext and you forgot your password and ask for them to email it to you (user: What the hell is this garbage of text, I didn't type this in!)
Unfortunately the above problems usually occur on sites where you need this most, and are very hard to solve, and so this problem is therefore unlikely to be solved "neatly" by anybody big.
Apple/Google/Microsoft can bake in cross-device syncing into the browser/OS and apply this sort of thing on form auto-fill.
It'll break down when:
a) Hashes don't meet site-specific password requirements (too long, missing special characters, etc.)
b) Sites store passwords in plaintext and you forgot your password and ask for them to email it to you (user: What the hell is this garbage of text, I didn't type this in!)
Unfortunately the above problems usually occur on sites where you need this most, and are very hard to solve, and so this problem is therefore unlikely to be solved "neatly" by anybody big.