I have an Oppo 203 and used the audio "only" HDMI to a HD621 and, more recently, a UHD722 with no problems.
My TV is 4k, and the Oppo drove the TV at 4k from its primary output, while the audio only output drove sound through the 861/UHD722 combination.

Cave: Trinnov Altitude CI-8; Oppo 203 Vanity HD; 6xDSP5k, DSP5kC, D1500; Sony Z9D, PS5 Pro; Apple TV 4K
Living: Wiim Pro; Rega Planar 1+; 2xDSP5k
Master: Wiim Pro; 2xDSP3100
Kitchen: Bluesound Flex stereo pair / Amazon Echo Studio
Deck: Wiim Mini; Random Chinese Class D; Cambridge Soundworks Outdoor 52s; Polk Sub;
Garage: Wiim Pro; 2x5k