If you change the target branch it will only show commits that are against that. I wish GitHub did that automatically because it has the parent commit tree but when do you that you'll only see commits that diverge from the target branch/pr.
Not really. I've tried that with Gitlab, but it's kind of awkward. My PR isn't to merge branch B into branch A. For instance if the project owners see the PR for B and say "yeah great! I'll merge this" and press merge, it will just merge it into branch A and then close your PR!
It's a hacky workaround at best. I want proper support. I want Github to disable the merge button until the dependencies are merged. I want it to actually list the dependencies and link to them. I want the target branch to be `main`.
I think if they did those 3 things it would go 90% of the way. Too much to ask though clearly.
Is that what you want?