Fully agreed.
Accessing Vaultwarden through a VPN gives me peace of mind that it can't be attacked.
Another great thing about Bitwarden is that it's possible to export locally cached passwords to (encrypted) json/csv. This makes recovery possible even if all backups were gone.
Yes, Bitwarden browser plugins require TLS, so I use DNS challenge to get a cert without an open port 80/443.
The domain points to a local IP, so I can't access it without the VPN.
Having everything behind a reverse proxy makes it much easier to know which services are open, and I only need to open port 80/443 on my servers firewall.