Hard to do within the marvel universe as they where defined by their stand against legacy heroes for many years. At best you have to look at street level characters in say Avengers or other teams. Super soldier serum heroes perhaps?
With DC it’s easier but they often go back and forth with editorial restrictions so consistent isn’t a common word. Batman universe characters tend to be similar and occupy the same spaces. GL clearly went to far. But it could support at least 4 heroes with the same green ring.
One problem with whatever logic Nick Lowe throws at us that we know that Marvel won’t be consistent. They only write rules like this to break them. If they come into a situation where a character they are excited for goes against this logic it won’t even be worth the paper it was printed in.