Does it fix the current UX issue with Squash & Merge? Right now I manually do "stacked PRs" like this: main If PR B merges first, PR A can merge to main no problems. If PR A merges to main first, fixing PR B is a nightmare. The GitHub UI automatically changes the "target" branch of the PR to main, but instantly conflicts spawn from nowhere. Try to rebase it and you're going to be manually looking at every non-conflic…
The github UI may change the target to main but your local working branch doesn't, and that's where you `rebase --onto` to fix it, before push to origin.
It's appropriate for github to automatically change the target branch, because you want the diff in the ui to be representative. IIRC gitlab does a much better job of this but this is already achievable.
What is actually useful with natively supported stacks is if you can land the entire stack together and only do 1 CI/actions run. I didn't read the announcement to see if it does that. You typically can't do that even if you merge PR B,C,D first because each merge would normally trigger CI.
EDIT: i see from another comment (apparently from a github person) that the feature does in fact let you land the entire stack and only needs 1 CI run. wunderbar!