From the side-lines it looks like they're slowly becoming an unstoppable dominant force, what's surprising to me is AWS's / GCP's inaction, they're either asleep at the wheel or they don't see Microsoft's dev mindshare grab as a threat.
And it was should have been rather obvious when GitHub released the beta of Actions a few years ago. Actions remains the most important thing GitHub has done, ever, in my opinion. It might take a few more years for people to fully realize what this could be. Hope GitHub doesn't screw it up!
The most important bit is workflow automation. It can be triggered on most (all?) events github emits
https://help.github.com/en/actions/reference/events-that-tri...
It was super obvious the value prop when it was HCL based. YAML based it kind of looks more like 'another CI'. It's still insanely powerful, just not as developer friendly anymore.