Yeah there are ways to run partial tests on modified code only. But they interact poorly with GH required checks. https://github.com/orgs/community/discussions/44490 goes into a lot more detail on similar problems people are having with GH actions - though our problem is with external CICD tools that report back to GH. Though it does look like they have updated the docs that are linked to in that discussion so maybe something has recently changed with GH actions - but I bet it still exists for external tooling.

It can be finicky to set up and mistakes can be made easily. Often you have to manually replicate the entire internal dependency tree of your project in the checks so that there are no false positive test results. There are some per-language solutions, and there's Nix which is almost built for this sort of thing, but both come with drawbacks as well.