Yeah, this is huge, especially for hobbyists. The M1 is a great laptop but being freed from buying one just to build for iOS is still cool.
You need to dedicate the instance for a full 24 hours, so if you're doing daily builds you'll probably end up paying for a mac mini every month.
Not that I'd ever do or recommend it in a commercial setting, but hobbyists should probably just fire up something like https://github.com/kholia/OSX-KVM to do builds.