Although Apple didn’t really officially announce this but some developers claimed it is and if so, then Plex and InFuse app can finally support bitstream of lossless audio like Dolby TrueHD, DTSHD MSTR/DTS:X MSTR and possibly Dolby Atmos as well. There is possibility that Apple only support Dolby Atmos up to DD+ with (JOC) capability akin to most streaming platforms like Apple TV+, Netflix, Disney Plus. We shall find out soon.
Source: Apple TV 4K Set To Support HDMI Audio Passthrough In TvOS 26