bitwarden_rs is definitely the way to go. I’ve been hosting it for my own use only for a couple of years now; never had any problems, and it’s a negligible drain on resources. It uses less than 20MB of disk space (15MB of the package, 2.3MB of icon cache, 408KB of sqlite database), about 24MB of RAM (admittedly it used to be about 13MB, but it’s still insignificant drain) and has an average CPU usage of less than 0.002% over 54 days of uptime (1:22.55).

Meanwhile the standard Bitwarden backend needs SQL Server and demands to have 2GB of RAM. No idea how little you could actually get away with, but I’m confident won’t be 25MB.