Bose QC35 headphones should be 100% functional over BLE without needing an app (I pair them with my iPhone as a normal BLE headset, and they pair with my Mac and Windows Desktop as well, no app installed).

Also, they include a physical audio cable which works all the time... I'm curious what could have caused your headset to not function normally, as I deal with many, many, many QC35s (my company gives one to each hired employee) and have never heard of (or experienced myself!) the app being a pre-req.