> almost all of these devices burn propane or similar to generate the CO2, making them dangerous for indoor use.

I'm not saying it's a good idea, but burning propane indoors is allowed for cooking and heating... although there's venting requirements and venting probably includes the CO2, so maybe not useful.

I use outdoor mosquito devices that have UV + a sticky tape with odor (supposedly, I don't smell it and can't confirm). I don't know how effective they are vs other things, but they do capture a lot of flying creatures anyway.