The other changes may be required if you want to detect if a video is already encoded in h265 and therefore skip transcoding but tbh I would transcode all videos which there is an option for. The transcoding process would probably still bring the size of the h265 videos and others down regardless of whether we deem them compatible.
I know client compatibility isn't your primary concern, but what's your use case for this with most devices not natively supporting this format? Are most of your members just downloading the videos off the MG?