It's wild to me that even just the API would be so controlled. Is it not enough that they control signing of the software? Does this not shoot them in the foot when it comes to courting developers?
What do you mean?
Specially small developers that would benefit from such free middleware...
The companies hold the gates to millions and millions of potential buyers. Indies want to sell in all of them and there is no other way for them to do so.
In addition, consider that most indies use Unity/UE, which already support the consoles, so vendors couldn't compete on ease of development even if they wanted.
If Godot was overwhelmingly used by indies, then yes, you could be right.