We have a solution to homework time thanks to a strategy they use with Older Boy at daycare.

He has a “choice chart”. It is 20 things which are acceptable to me (and not disruptive to Younger Boy) that he can do while Younger Boy is doing homework. His job is to keep himself busy with things off the choice chart. It is mostly five minute tasks and he has to do a lot of them each day, but it seems to be working.