The Godot foundation picked MIT for a good reason. If your legal team says no GPL then no GPL. This has been standard practice for decades.
The changes you make to a game engine are almost never the important part of your game's IP.
I guess you could sell the game ready to play, and then upload its source code without needed assets somewhere else.
Most companies aren’t going to be ok with this.
I know when I write a project, I just MIT license it. If some of the code I wrote helps you get your job done, go for it.