is there a reason you need to rely on a provider and not use an Ubuntu install of the OS and then add the KStars related repository in manually.
It's not that hard and only takes a few minutes more to do. I had to do this when I was playing with an
Orange Pi3 LTS
when the RPi4 was not readily available. It honestly was not that hard to configure Ubuntu and then install the associated astrophotography software. I played with the Orange PI 3 for a while until I moved over to a mini PC solution.