Use a board view, and use rows as groups. there that can be filtered contextually. No idea why context filters work there, but not on other groupings, but this could be a solution for now. You can set the board view items to “line” then it looks like a list.
And i personally prefer the UI of the groups like this as well, but maybe thats just personal preference.
Down side is it only allows for one level of hierarchy, but in this case I think thats okay.
Curious if it solves it.