I won't disagree. It should be easier imo. I guess this is why a cottage industry has sprung up addressing such e.g. https://news.ycombinator.com/item?id=39930908

It's actually pretty easy.

Setup GitHub app. Install the arc helm charts. Install a buildkitd statefulset.

Update parans on build to use buildkitd.

That's not to say there aren't better caching strategies, but a really basic ephemeral setup is right there.

runs-ons supports custom images - https://runs-on.com/features/byoi/ and caching to S3 - https://runs-on.com/reference/caching/

I haven't used it yet but these two features make it the clear favourite for me in alternate github action runners