There's one small missing feature in GitLab/GitHub/etc that I've never seen anyone talking about, and I don't know why.

Imagine you work for a regular boring old company that isn't big enough to have gone down the complicated route of using a monorepo. You might have a couple of applications and a shared internal library that supports them in three different repositories. Today, if you want to make an API change in your internal library you need to make three PRs. One to the internal library and one to each of the applications that depend on it. Currently these have to be created, reviewed, and merged completely independently even though they're all part of the same change.

Instead, why don't we have 'grouped PRs', a cousin to the recent 'stacked PRs' feature on github/gitlab. When you push multiple branches with the same name (or manually select some) across different repositories, creating a PR offers to create a group PR:

These show CI checks from all involved repositories and all other metadata as usual:

Then, the main attraction, a single diff/review page that shows changes across all repositories:

Now the idea is out there I'm hoping someone will implement it!

All writing is my own, LLMs were used to generate the mockups in this post.