Woah that's actually huge. I've been very interested in tangled from an atproto perspective but I had no idea it had that as well. Wonder why that isn't talked about more. Seems like an amazing feature to potentially pull some people away from GitHub/GitLab after they've have been asking for years for a better stacking workflow.
I've been going through a lot of different git stacking tools recently and am currently quite liking git-branchless[1] with GitHub and mergify[2] for the merge queue, but it all definitely feels quite rough around the edges without first-party support. Especially when it comes to collaboration.
Jujutsu has also always just seemed a bit daunting to me, but this might be the push I needed to finally give both jj and tangled a proper try and likely move stuff over.