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 fo

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.