What are your findings on the AppleTV 4K with Infuse Pro? Are you getting DV at all with it? I have tried many of the options here in this thread and haven't been able to get DV with this, if it is even possible? I have done various combinations with DVDFab, MakeMKV and TSMuxeR.
There is no real DV from Infuse Pro on the ATV from UHD-mkv's, but you can be tricked into thinking it works. Very occasionally, my ATV will re-set its DV enabled status and invite me to "try Dolby Vision". On enabling DV, you need to be careful that the system settings have "match range" enabled for dynamic range. Otherwise, you'll get the DV logo on your display when playing an mkv, and at first I thought that meant DV is working as I was playing a DV mkv, but then found out I also got the DV logo when playing an HDR10 title. The reason for this was that match dynamic range had accidentally got disabled. When match range is enabled in system settings, I always get HDR10.
Couple of issues to consider with the ATV: no passthrough of DTS-HD/Dolby TrueHD, but Infuse will output hi-res PCM as far as I can tell. I have surround channels but not overhead, so for me I am ok with Infuse but lack of hi-res passthrough could be a dealbreaker for some. Also, I noticed that ATV/Infuse seem to use weave deinterlace on everything. So native 50i material is unwatchable on the ATV, as it throws away the 50Hz motion. It's ok with TV drama that is progressive at source but authored in a 50i stream (lots of UK TV drama is like this), but just dreadful for genuinely native interlaced material (e.g. older studio TV material). This may be a general issue with the ATV, not just with Infuse. I looked briefly at Plex, but lip-sync on the ATV with Plex is such a joke the demo did not last long.