I have a hacky workaround workflow, not sure if best practice.

When feature A on branch A is pushed to GitHub/equivalent and in Pull Request, and you need to work on feature B that depends on A, then work on feature B while staying on branch A, just don't commit or push, just work on it locally.

If you need to update feature A e.g. for a bug fix, stash local changes for feature B, fix feature A, push to branch A, then stash pop and continue working on feature B.

The only gotcha would be if the fix to feature A has conflicts with your stashed changes for feature B.