I understand this is from 2+ years ago, but some things never change. The desire to customize MacOS, as well as the incessant drum beat of "nope you can't do it." Other wrong answers include:
- Embrace change
- it's better this way
- Once you get used to it, you'll like it
I happen to believe that the UI of an operating system should be customizable. I want it to work MY way. If that means mapping the caps-lock key to cycle between workspaces, that's my prerogative. If I want to change window toggling so it works like KDE/Gnome/Windows, that is my choice.
And I want a 'start' menu on MacOS, that is between me and the universe.
Another fundamental that never changes: Where there's a will, there's a way. I'm pretty sure I'm not alone in wanting to customize the heck out of OSX considering how many tools out there are designed for exactly this purpose. Check out the tools written by manytricks.com (No affiliation). Their apps are not free but look promising.
Rather than trying to make it look completely like Gnome, focus on specific annoyances or things that slow you down. Whether it's alt-tab or other behaviors you want. Focus on the behaviors you want changed and you'll probably find tools that will do what you want.
One word of caution: Many of these tools require the "accessibility" feature of the OS. If your employer has turned that off in the name of security, you might be out of luck.
I'm sorry to say, the best I've found is articles on how to make MacOS look/feel like Windows, not X/Gnome/KDE. You may have some luck reading through those articles and picking specific UI behaviors you want.
https://www.digitaltrends.com/computing/how-to-make-mac-look-like-windows-10/#:~:text=How%20to%20make%20your%20Mac%20look%20like%20Windows,switching.%20On%20Windows%2C%20Alt%2BTab%20cycles%20...%20More%20items