So much guessing, not a lot of facts in this thread. macOS has no problems mounting the camera in CDROM mode to install DCU or in MTP mode. In MTP mode, it doesn't show up as a mounted drive in Disk Utility, which means that it is safe to just unplug the device. See
this discussion for screenshots on how to verify that the camera is not seen as a drive in Disk Utility.
This from Apple support (found in the discussion linked above) is Apple officially giving a list of steps that involves just unplugging the camera.
I personally prefer card readers to connecting my camera directly to the computer, but I have just tested all this with the K-3 iii and it works described above.
@Marmimag can rest easy just unplugging their camera from the computer.
---------- Post added 05-09-21 at 10:44 ----------
Originally posted by i_trax
Is K-3lll compatible with USB C / Thunderbolt 3?
It has a USB-C port on it, which was one of the little added perks that Ricoh has been touting. This seems to be part of why they aren't shipping a standalone battery charger with the K-3 iii, and allegedly, whenever they get around to updating Image Transmitter 2, the K-3 iii will tether over USB-C at really good speeds.