After a lot of very frustrating experiences, I have found that I am unable to use any of my Pentax cameras with :

IndiLib/Kstars/Ekos.

I have tried a K01, K1ii and K3iii, with a Raspberry Pi 4B 8Gb. I have tried with the native drivers and the legacy drivers. I have tried with the base CCD driver.
It will connect with the base Gphoto CCD driver, but I have yet to achieve any sort of communication beyond that. It will not connect with the Pentax drivers at all.
LSUSB shows the devices, so all are available.I have tried with a different Raspberry Pi 4b 4GB as well with the same results. I have tried compiling from source, and I have the same result.

From the forum posts I have read, a few people are still having success with legacy drivers on the K20D, but nothing since then. It appears that at some point in time, the drivers have become broken.
I am exploring what needs to happen to recover some capability. It would be fantastic if anyone can share their recent experiences with Pentax.

Thanks,

Ian