Answering parts of your question (I don't use the stellarmate app):

I do what you suggest at home (powerline networking and VNC--really NoMachine) and it works fine. I actually connect a switch to the powerline so I can plug in a laptop outside near the telescope, should I need to (my home WiFi does't reach my home telescope's location), but I primarily access the scope using NoMachine across the network from inside my house via the powerline network.

I would think you should be able to polar align your scope outside with the standard linux-based KStars/Ekos program, then disconnect the laptop-based KStars/Ekos and reconnect to the app. As I said, I have no experience with the app, but I would expect that to be fine.

Also, if you're using the latest (v3.6.0) polar alignment, you can choose the "PlateSolve" method (instead of MoveStar) and then there's no need to click on any bright stars etc. Not sure how/if that's implemented on the Stellarmate app. See indilib.org/forum/general/11816-announci...changes.html?start=0

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