For private repos and work stuff, we are working on actuated, which comes with unmetered billing minutes because you BOY machines or cloud instances.
ARM builds show to be ~ 20-30x faster than using QEMU too.
https://docs.actuated.dev/
It was up on Hacker News recently, so you may have already seen it.
https://blog.alexellis.io/blazing-fast-ci-with-microvms/