Looking at the port on the Z790-I's HIVE, I would interpret the markings as it being a hybrid port that can do either analogue electrical 3.5mm mic-in (just standard mic port), or mini-TOSLINK optical S/PDIF.
You could use a ROG Clavis DAC if you need both mic-in and optical S/PDIF.
Yeah, both the optical side and the S/PDIF protocol/format are the same for both sizes of TOSLINK. It should work fine, in theory anyway. Fancy Hi-fi stuff can be temperamental sometimes, so good luck.