POV camera footage without holding your phone out in front of you distracting you from having to look down at your phone instead of up at the thing you're filming? Imagine you want to capture your POV but also want to be present and in the moment, not looking at a 6 inch rectangle screen to check your framing of what you're capturing.
Go-Pro on forehead? Thats what outdoor enthusiasts do. If you need to make room for a headlamp then pin it to your jacket maybe.