The SDUC standard exists, but no, there aren’t any commercial 2TB microSD cards yet, though they’re coming.
The World’s First 2TB microSD Cards are on the Way
Micro SD card storage and data storage technology, in general, are advancing all the time, so large space volumes aren’t much of a surprise, except when
Everything except for the UHS-III part, yes. Some UHS-II stuff exists, but I think it’s limited to full-size SD cards right now, and the Deck only has a UHS-I bus.