YMMV:
I find Act cool in principle, but whenever I try to use it locally on my Windows machine for any open source repository I haven't authored, it just doesn't work.
That is to say, the repo authors use features like "sudo" in their jobs, which fails in Act (weirdly even using the larger base images - after those cloned for >1h), or they otherwise rely on the fact that the Github runners run natively on Linux.
It's a real shame, too.