Pretty please 🙏🥺 The repo is broken without this.

Here's a better explanation of what's happening: On the latest state of staging, CI checks for new rust toolchain updates, verifies everything still works fine and then pushes to main. Nixpkgs had a change that introduced an error at the verification step, so no toolchain updates to main from there on. It was easily fixed though (just required pname which wasn't set before). The fix was merged into main but not into staging, which means CI still fails and won't update mains latest toolchain. Hence, the repo is stuck on rust 1.85 while 1.86 is out already.

It would be intersting to know indeed.
From my personal experience, (I glance over the load of our 3 community builders regularly), I would say that the "average" LAV is quite low.
I.e., they are unused most of the time.

This doesn't say too much as when a build is occuring, they can very quickly be overloaded.
Some nix mechanism to prevent that (such as the work started by emily) would be very helpful.
Ideally a SLURM-like scheduler with a karma score would be the best way to share limited computing resources between several users.