For anyone looking to stay on an open source solution: Keepass databases, synced using whatever sync tool floats your boat (syncthing, Nextcloud, iCloud etc.)

For anyone looking to stay on an open source solution: Keepass databases, synced using whatever sync tool floats your boat (syncthing, Nextcloud, iCloud etc.) On Android I used KeepassXC and syncthing. After switching to iOS: Keepassium + NextCloud.