Use the “passwords” feature to check if one of yours is compromised. If it shows up, never ever reuse those credentials. They’ll be baked into thousands of botnets etc. and be forevermore part of automated break-in attempts until one randomly succeeds.
KeePass and syncthing. I use Keepass2 on a Linux desktop and laptop, KeePassDX on Android, and use syncthing to keep everything synchronized and up to date, also using an old raspberry pi to act as a central server for syncthing.
Modifying the database on one device seamlessly updates the other devices once they’re visible on the network, everything works beautifully and is very easy to set up on a local network.
Pretty much default configuration all the way around, just gotta make sure syncthing starts on boot. Just did a brief search, syncthing seems to have a MacOS fork, and iOS will need Möbius Sync, which is paid but the free tier offers 20MB storage sync which is overkill for KeePass.