I just thought to add that I was able to natively build INDI v1.9.3 with some INDI 3rd party drivers, stellarsolver v1.8 and finally KStars (github commit 6782a28d34d354ba1a73f173afeffbe0157bea15) on a Raspberry Pi 400 (4GB RAM) running Debian Buster arm64. I am novice and learning to use INDI/KStars; things seem to be working but I can't say I've tested thoroughly.
I went through each step manually, referring to the build instructions from each project as a guide. It went smoothly, however I scribbled some notes that I think related to packages I had to install instead/in-addition-to some similarly-named ones in the instructions: kio-dev, libqt5datavisualization5-dev, libkf5notifyconfig-dev
My 4GB Pi ran out of RAM while making KStars with -j4, but succeeded on a retry with -j1.