Gregory's Server
On my 2nd job we're developing "MST" -- an open source/free software solution for multi-seat configuration:
https://gitlab.com/gkaz/mst
To test it in production we've deployed MST on several workplaces in our local college and it works quite nicely.
Currently I'm working on packaging MST for GNU #Guix (see "guix.scm" file in the repository.)
In 2020 I gave a talk (in Russian) about MST:
https://0x1.tv/20200208A
MST uses Qt for GUI and the #Scheme (#Guile) for its daemon.
MST allows to configure a multi-seat setup without the requirement to use a separate GPU for each seat; you can theoretically have as many seats as the sum of your GPUs outputs.
The project was started because the existing multi-seat solutions (that we were aware of) were either proprietary or clunky at best back then.
Currently I don't getting any funding for my work on MST but I'm hoping that the project will be of some help for people.