This is great! I didn't know this existed, but it looks like for self-hosting this is a much better solution than BitWarden proper (as it is lighter). This shall go on my synology.
VaultWarden is fantastic! It's super, super light and fast (Rust + sqlite) and happily runs on my Raspberry Pi 4 4GB in docker alongside 8 other containers. And if that wasn't good enough, all the 'premium' BitWarden features are also unlocked (organisations, etc.) in VaultWarden.