It's available to everyone, all of the time. Anyone can do it, which is why you actually see forking and custom tooling quite frequently in businesses at-scale.

It's absolutely bewildering that someone would say "it's not going to make a difference" when half of the market for B2B software is literally predicated on the existence of more permissive tooling. Licensing is practically the only thing that matters besides security and functionality when evaluating software.

I'm not sure what you mean by this? I would guess from my own experience that there are open source alternatives to the majority of software. Often the open source software is just as good or better.