I looked into this a bit more and here is the summary: This is meant to show off a candidate kernel feature that allows for running different schedulers in userland.
Task scheduling has become much more complex as CPUs have grown in size and have had new developments in architecture, so the need to develop more complex and robust schedulers is steadily rising.
The kernel feature is meant to lower the barrier of entry for anyone who wants to try getting into schedulers, as well as enable quicker development iteration, by removing the need to completely recompile the linux kernel every time you want to test your code.
Read more at the main project's github: https://github.com/sched-ext/scx
Thank you for the correction! Reading up on eBPF is fascinating.
Additional resource that adds to your secondary point that this is more than just allowing schedulers to be run in userland: https://github.com/sched-ext/scx/blob/main/scheds/c/README.md