How about good 'ole stufed peppers? I’ve never made them with bell peppers, but it works!
It might be too late for the ones you’ve picked, but have you considered letting them ripen? I grow “Italian frying peppers”, but I think any pepper allowed to ripen can be frozen, after cutting flat and frozen on a sheet pan.
With ripe peppers you could make red pepper paste or roast them and make into things like roasted red pepper soup or freeze roasted like that to use later, or maybe make piperade or peperonata first.
I really like ripe peppers, and the long tapered ones , like the long Italian ones are easier to grow here than bells.
Some piperade recipes, like this one, probably behind the NYT paywall. are made with green peppers.
