I've been using KeepassXC (KeePass w/ macOS GUI elements) and enjoying it. It's a little simple (you just copy and paste the PW). It doesn't do fancy autofill but there's support for pretty much every OS. (I use Spideroak to sync the DB across devices)
KeepassXC does have a browser extension for Firefox & Chrome. I use Syncthing to sync it among devices, it's open source and fairly simple to use(compared to other DIY cloud apps)
Yeah, but IIRC it doesn't on iOS? I dunno, it hasn't been a big pain point.
My solution has to use the Firefox password manager for low value things (like Hacker News), and manually c/p for the higher value (bank, retirement account, etc).
(Maybe I'm overly paranoid but I don't like to put high value passwords into the cloud)