Set a GitHub runner on one of those free Oracle Cloud ARM64 instances.

Sure that is doable, but it doesn't quite sound like a OOB solution where you just add a flag to your YAML, or another line to your build-matrix and call it a day.

I've honestly missed this on Github Actions, and hadn't (yet) found a simple enough workaround to bother.

But it is also set and forget kind of thing.

If it’s that easy… git a link to a quick howto? :)

Does it work regular (free) accounts, free organizations or other similar setups used by non-commercial open-source projects?