I just got these brackets:
https://www.amazon.com/gp/product/B06WD81PLL/ to use with my Huewei Mediapad
M3. The S-Holder on Etsy is similar in concept, but does not have the lanyard. The brackets I got allow your hands to go under the tablet along the curvy part of the bracket, and grab the controller in a very natural way without much obstruction from the tablet at all.
These just arrived yesterday. I did fire up the app and turned on the MP, and all seems to work with this tablet, but I have not flown with the tablet yet (I've been using an LG V20 phone). I'll report back, but my guess is that the processor on this is definitely sufficient for this purpose. Unfortunately, the screen is not as bright as my OLED Samsung Tab S 10.5, but that seems awfully big for this purpose, and given it is going on 3 years old, the battery life on the Samsung is not great (even though I have replaced it). The Huawei battery is great for normal usage.
I am probably going to be looking for a nice sun visor for the Mediapad
M3, but it seems the 8.4 inch screen is a bit non-standard, and the 7.9 inch visors will not be wide enough. I'll snap some pictures of the tablet with the bracket and post back.