We already made a huge progress in making 5 UI projects using similar tools. That way it is easier for developers to switch between projects.
There are still leftovers. At least:
Migrate to Jest in Stage
Migrate to React in Topology
Composer/Stage backend test placement
We are good for now. 2 from 3 points already done. Migration to React in Topology is huge thing, there is separate epic for that (CY-2655). Closing this issue.