I bought this as soon as it came out due to using the Nyx in the field and experiencing some problems with runaway and the difficulty with using a mobile phone interface in the dark of pressing the wrong buttons by accident on a smooth screen while doing other activities.
It is acknowledged to be a variant of the OnStep SHC and so I expected the features to be the same. Largely they are but some things are different - for example:
The rates are speed multipliers (48x, , 1/2 max) rather than as per the Nyx software console on the PC ( 1degree/sec etc)
There is no backlight. That's not a problem in the night but the screen is invisible in the day for use in solar astronomy. I checked with support on this - it is not adjustable. Just the contrast.
The time and date adjustment procedure is awful - relying on longer presses to adjust the speed of change of the entire date, not just each group of digits. Its very easy to miss and overshoot and spend time fiddling that you'd really rather not.
I stlll experienced some overshoots - ie the mount doesn;t receive a stop. Thats probably a mount issue since it happens with both the phone and the handset. It doesn't happen often at all but it has happened while trying to demo to other interested parties.
The manual was released after the handset. It helpful to know some of the button maps to escape out of the alignment procedure for example. (https://pegasusastro.com/wp-content/uploads/2024/07/NYX-HC-Manual.pdf) but doesn't describe the pin-out of the ST4 cable.
The handset is powered by the mount. It should have a battery-only mode but not in this variant.
Hope this helps.