Did that years ago when I switched back when Quantum came back; Firefox still has the good old venerable "import passwords from another browser" functionality. You just need to have your passwords sync'd to a local install of Chrome and Firefox can read them all and sync them with FF Sync (which does not force you to use Mozilla servers, btw; you may host your own server for max privacy).
It's not just their service. You can run self-hosted service for sync [0] and fully control it. From privacy point of view that's far more interesting than any other solutions I've seen.
I've been doing this for a while but the part I haven't managed to solve is that using your own sync server on Firefox for ios seems to require you to also run your own Firefox accounts server - which is much more painful to set up. Is there a similar easy guide for setting that up?