The more I use this setup, the more I feel like giving this advice:
Try it by connecting to the Pi using a computer inside, even if that is not what you planned. The setup will be slower because all the images are now being transferred to your laptop. But with the much bigger display and UI, it is easier to troubleshoot issues. If image transfer is too slow, try binning. I troubleshot my speeds by running iperf server on my computer and running iperf from the terminal on Rpi. If you live in a cold climate, just try to power the Pi using an electrical outlet rather than a battery to see if it makes a difference.
I struggled a lot with this setup, primarily because I had not done this before. A lot of it was just a difference between how I think it should work vs how it actually worked. I had never worked with an astro camera, so just getting an image to show up was an exercise in frustration that I had completely not anticipated. This affected everything from pointing the telescope correctly, focusing, slewing not succeeding, etc. But again, large display, I not being outside, etc. helped me stick with it. Admittedly I don't have the same mount as what the OP suggested and a lot of the problems here have to do with specifically Az-Gti being wired.
I even went one step further and used Ekos for image acquisition, then stacked using Sharpcap Pro using folder monitoring. That way I could confirm that everything other than Stellarmate's image stacking was working. Personally I decided to remain with Sharpcap Pro for stacking simply because I can do some curves adjustment. But you don't have to.
Finally when everything else works, and you still cannot see live stacked images on your phone/tablet, you can then concentrate just on the live stacking part (i.e. play with gain, exposure time etc. to see what's the sweet spot before the Pi gets overwhelmed)
