How is bandcamp involved here? I’m curious now

Put simply, a bot that interfaces with external services and replicates messages to/from a Matrix chat. The software is at matrix.org

Which bridge did you use, if I may ask?

Maybe try a Matrix bridge?

There’s this project: https://watchit.movie/#/ https://github.com/ZorrillosDev/watchit-app

I never got to try it, but they are doing exactly what you want it seems. I don’t know how much of their backend they have open-sourced, though. I definitely need to research this more.

They do have a matrix channel and a fediverse presence, so they already look quite alright from the start, and the project is very interesting.