I feel you on the engines not doing it for u. This could be the place for you my friend.
That depends on what you value. If you want to crank out your game ideas as fast as possible then using an engine will be the way to do that. If speed is less of a concern and you want to learn a bit more about how things work under the hood and then have more control and freedom (and pride) because of it then something like monogame will probably be better.
Engines are opinionated. You learn to do things in them in a certain way and you may not learn why or even realize they could be done differently.
Not per say.
Depends on your definition of a real game. Give some examples!
If you want to quickly build something robust with clean code that scales well: yes you need to be an excellent developer. If you have low expectations on those things, then no. As you’re willing to put in the work and learn, what you can do will expand with your experience and understanding of the concepts involved.
Here’s a thread with some monogamers discussing why they chose monogame
Welcome to the MonoGame community,
happy coding!