That doesn’t sound right. My photo library is larger than my iPhone’s storage yet downloads fine on my Mac. Just need to make sure “optimise storage” is enabled on the iPhone and disabled on the Mac.
Once everything’s downloaded on the Mac, you can either export through the Apple Photos menu or just copy the “originals” directly from the Photos bundle.
And people say Linux is hard to work with....
This works because you had synchronised your iPhone with your Mac previously. If you start with an empty Photos library and phone, it is impossible to put all the photos on the phone and thus transfer them to your Mac.