This was the first time I attempted to edit GoPro Hero 9 footage alongside iPhone 13 HDR footage, to generate and output an HDR clip for YouTube. I won't lie and say it was easy, but there were a lot of things I learned along the way that really helped, and I think I could do it MUCH quicker next time.
I use Davinci Resolve for my editing and there are a couple of really good videos out there that walk through how to set things up. The important thing to remember is to set the color management in project settings to Davinci Color Managed, HDR, HDR HLG. For output, you should output in Rec.2100 HLG. If you have any questions, definitely comment and I'd be happy to walk anyone through it! I was really excited when I first saw the "HDR" tag on the video on YouTube!
I think it turned out really well and the footage from two different cameras blended fairly seamlessly. 90% of the footage is from the GoPro Hero 9, with very few clips brought in from the iPhone. Let me know what you think!