I use KeepassDX on family mobiles with Syncthing for copies between laptop and phones. What would i gain moving to Vaultwarden, knowing that i would never open my network to the outside world? It would be easier to manage for sure, as im having to setup phones and laotops myself in the family and worry that they do silly things like turn off syncthing. But what about offline access to passwords? Does Bitwarden mobile client keep a local copy of database until it can sync?
I too use Keepass2android offline, never had a sync issue though recently I inexplicably encountered an issue where the keyfile couldnt be found or had become corrupted on mobile. This may have been a phone thing rather than a Keypass thing as I never had such issue in many years of use. Luckily I had the forethought to keep an encrypted backup so I was back up & running quickly.
If I remember Keepass allows pdf attachments without restriction which is excellent for vehicle insurance, breakdown cover etc as its good to have these available offline anytime “just in case”. I think this feature is restricted in Bitwarden (though maybe not Vaultwarden).