You can you use handbrake to export H264 10 bit on a Mac its free and no command line is needed it also retains all metadata needed to flag the HLG flag on youtube. You cut your upload time but you increase you render time... compression doesnt come for free unfortunately. Have you tried playing the 10bit 422 HLG file that comes out from the camera and it doesnt work? Sounds strange that tv doesnt play 422 files since that cancels the whole HDR wide colour gamut thing. You can also export VP9 directly from Resolve.
I am sure it will take me much more time to complete a project in FCPX than in Resolve since i have no experience in FCPX. I think its just what you have experience with. Not that Resolve is easy to learn in few days.
From what I understand UHD premium requires 10 bit colour and additional dynamic range but not 422 which is just the way the colours are mapped on the frame. My understanding is that 422 is required mostly for grading but then once done you don’t see it.
My Tv LG OLEDB7V can display even 444 but the player can’t process the files
I use handbrake and with ffmpeg can also convert the camera files to prores free
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