I don't have much sparkling insight to add, but I do have a couple of thoughts and one article that seems appropriate for the thread.
First, you have to find out what really causes him to not like school. You can't just ask him (although obviously you do that too) you need to figure it out because he's not going to tell you the root problem easily. That's just the way kids are. You can't figure out what your best response is if you don't really understand the problem and the root cause of the problem.
Second, it does seem like he's doing a lot for a kid his age. Does he have time to be a kid? Can he go to his room and lose himself in a book for an afternoon without anyone bothering him or is there a nightly race to get home after activities, a fight to get homework done, and straight to bed the second all the work is done?
My brother is a school psychologist and he claims there is NO correlation to completing homework/grades/success in the lower grades and success in high school or later years. From my experience (and woeful grades) I think he's right.
Finally, here's a good article I literally just read. As I read it I thought of this thread and thought I should post it. So here it is.
https://www.theatlantic.com/magazine/archive/2019/12/stop-trying-to-raise-successful-kids/600751/