There's compatible Bitwarden server written in Rust called bitwarden_rs[0] for those who don't want to run the official Docker image with the requirement of Microsoft SQL Server and the demand for 2GiB of RAM.
[0] https://gist.github.com/Checksum/5c604c8d1180dd060aebf510262...
Says it works on Raspberry Pi 2 or newer. Do you have a 1?
It felt like a hidden cost to run the official server as I had to upgrade my server instance for an extra $5/mo.
Do you get TOTP support and Organizations on your custom server for free?
EDIT: I just tried it, and yes, you do get (at least) TOTP support for free. Haven't tried orgs, but I'm going to convert it for Dokku now and host it somewhere as a backup plan.
I don't think this is the case. There's really no way to use the license with a custom server anyway.