For companies with resources for infrastructure, sure.
For OSS, the unlimited free minutes of multiplatform CI offered by GitHub are literally impossible to replace. Maintaining runners yourself to do the same things would be somewhere between a part- and full-time job.
> For OSS, the unlimited free minutes of multiplatform CI offered by GitHub are literally impossible to replace.
Yeah, how you think the ecosystem got by before GitHub even had actions? Y'all don't remember Travis CI et al anymore?
There are more CI services than what Microsoft offers the world, sometimes it's worth looking around a bit.