Oh, okay. I just tried the picture in picture feature, and it seems to do what I want (play when the phone screen is off). So, this feature is already supported. Thanks for letting me know.
Take what I am about to say with a grain of salt because I am old, and more comfortable on regular computers than mobile devices. Having said that, I had no idea that the browser had picture in picture until you mentioned it. I immediately went into the settings to see if there was a toggle that I had to enable. I of course didn't see anything. So, I started up a random youtube video and STILL didn't see the option -- not until I put the video into fullscreen. And then it was there and worked wonderfully (you guys have created a wonderful app).
So, is it largely undiscoverable? That was a lot of steps that I took (albeit a short amount of time). Or, is this something that the average user who is more accustomed to using mobile devices would expect? I honestly don't know, just throwing it out there. Thanks again.