10 inch and a mount I’ve done it wiith iPad and also had iPad mini never happy needed also fit a sun shade as screen was not bright enough but these are useless imo. did a search and seen alot of people used nexus 7 2013 tablet, I bought one for £30 from eBay, stripped it back so only Google apps and only use it for the Mavic.
Since using the nexus 7 I’ve been very happy as the screen is much brighter higher nits compared to most and no need for sunshade or mount as it will fit to controller arms also 2 gig memory I think really helps.
I have a backup phone I use a oneplus5t fast and bright but always use nexus as it’s so easy.
Crystalsky be my dream setup but costly, I will be going away from tablet when I take the plunge and buy a moverio bt-300
This will give you some help.