If you are comparing buying the device + the other costs of running the device vs renting from aws, then the 24h upfront is not an issue. You could even consider renting for a year or more.

Certainly it's going to depend on your use case.

On my team, we just have a Mac Mini sitting under someone's desk to do stuff that requires a Mac. It gets used for about 1 hour every day for a daily build. For us, AWS's offering doesn't make financial sense.

Even if we were to switch to only doing a weekly build, it wouldn't be worth it, as that would still cost around $1,250/year.

Yes. The details don't particularly matter, but broadly, it's periodic QA of a couple of apps & tools vs Safari, vs OSX, and vs homebrew. Not CI/CD.

OSX seems more prone to bitroot regressions than Windows or Linux, I suppose Apple have a "you're with us, or you're against us" attitude and this even applies to base OS backwards (in)compatibility.