Is there a headless (non-UI) version of Fopnu that I can run in a Docker container on a dedicated server and access remotely?

No. There's no web UI or CLI. I've ran fopnu on a server but I had to use VNC to remotely access the desktop.

I'd love to see a headless version. I've got a dedicated server with 10TB space and a 10 Gb/s connection. I'd love to share some of my files, but it's a headless Linux server. I guess I could try run Fopnu in a Docker container that uses VNC (which is how I run Soulseek today) - will look into it if I get a chance.