Bitwarden is not written in Rust, it's a C#.NET with MSSQL beast, so self-hosting is not for the faint of heart. However there's an open source reverse enginee

Bitwarden is not written in Rust, it's a C#.NET with MSSQL beast, so self-hosting is not for the faint of heart. However there's an open source reverse engineered server, called vaultwarden (previously bitwarden-rs) that is indeed in Rust and quite slim. Both can be used with the official clients (which are also open source). Besides that, yes, Bitwarden is amazing.