Yes, I continue to use the Pi4. But I got my Pi4s before they had the chip shortage. If you are planning to buy one now, you pay double the price for an 8GB version (definitely get 8 GB) and at that price, it is no longer competitive to NUCs, I would say.
Perhaps a better alternative would be an 8-core OrangePi with 16GB RAM for $132 on Amazon plus cooler ($20). The downside there is that the Ubuntu image for it is not the generic US Ubuntu version, but a Chinese version. I am not certain whether that might throw an error when you are compiling kstars on it. Have not tried that. I am using it mainly as a mail and video server so far. It also sucks a lot more power. You need a 4A power supply to run the OrangePi.
I gave detailed instructions somewhere else here on how to install Ubuntu on the Pi4. It was pretty straightforward. In fact, now you can just download a complete image from the RaspberryPi.org website. Even simpler. After that, it is just a matter of installing kstars.
The main problem I have with kstars is that after updates often some of the drivers fail and I need to recompile everything from scratch. That can be a major pain, so NEVER update before an imaging session. You may just end up missing much of the night.
Hope this helps.