I know this topic it is old, but I found myself in the same situation, with an Oly EM1.2 and an A7r cameras not willing to work with Kstars and Ekos.
So what I did, is try to find which version of libgphoto2 was on my Raspberry Pi 4, and it turned out to be last version available.
Then I tryed to see gphoto2 and it was missing on my system, so I used this command line to install it manuall:
sudo apt-get install gphoto2
And it worked out.
After doing this in a shell, I restarted Kstars, and Ekos, setted all the configuration of both Olympus OMD EM1.2 and and it worked like a charm. I tryed only to record the RAW files on camera, in the SD, and it worked.
On my A7r it worked but I couln't make the RAWs to be recorded on the SD. I don't know if it was a config problem or other cause.
Maybe someone can have some help with my findings.