All of the concerns you mentioned seem to be based on managing people's time instead of their output . Except the first one, 5-10 minutes is a normal break, so it wouldn't be anything notable to me how one chooses to allocate their break. They'll produce better results overall vs not taking an hourly-ish break.
Agree on games. I find it hard to manage output alone, it's a combination of both. Do you count hours where you work? How do you manage output? To me output is challenging, because any engineering task can take less or more time that what's estimated and thus how to set a realistic goals for the team members without making them go crazy.
Managing output over hours is definitely challenging and probably more of an art than a science, especially in an agile environment. I've found sprint pointing can help but is still pretty imperfect. I don't know if anyone necessarily does it super well, but as a manager you can help motivate and manage expectations so that your team members are each giving it their all and doing work that they care about. IMO people don't need much motivation when the work is interesting.
I'm starting to experiment more with time boxing vs scope boxing personally. Definitely a challenge in environments where scope is not clearly defined.