One problem with those designs is that cramming the entire GIMP's menu into the hamburger menu on top right is likely to cause more problems than it solves.
This stuff sort of works in applications with a limited feature set, such as Akira UX. I don't think it can work well for GIMP.
It's possible to find a hybrid approach, but so far, I've only seen Siril doing that, and I'm not convinced.