What you are saying is correct, and why I am looking for a better way.
It was just simpler for me to set up a complete image that can be used on a VM.

I have seen other similar projects where the setup is a hassle, which is why I am looking into it.

(changing requirements, custom scripts, extension)

I did it to save on space, LXDE could also be an option but with a bit more space.

I remember a teacher requiring us to use Matrix for a coding class. We still mostly used Discord, and after that class ended, we never used it again.

You and I have a reason we use Lemmy: we don’t want to use Reddit and want the Fediverse to grow. Simply forcing your students to make Lemmy accounts won’t do anything, in fact it might make them hate it (Oke boomer).