Another cool website that I came across a few days ago is https://vdo.ninja/ (create reusable invite option) which also uses the HTML camera APIs to connect your mobile phone to OBS. Both the audio and video quality I get from my phone is at par or sometimes even superior to my laptop's webcam. This video tutorial(1) explains the setup really well.
Kudos to whoever made this free site and also the modern browser tech for making this possible.