I just installed Catalina on an additional backup of my working Mojave installation (iMac 19,1). During my install I had a pretty smooth progress bar counting down from 26 minutes (nothing like in
CaseySJ's post described). The system also did not restart. After the installation process I started from the external disks MacOS portion (no Installation partition left) and had one more progress bar of 9 minutes with the Apple logo before I could log in.
There is a chance, though, that I just missed the first phase, as I initially had one problem:
During the first boot of the installer, my screen just went black after the verbose went through (a lot longer then usual with some problems detected. So, after a few minutes I just shut the PC down, thinking it wouldn't work. But in fact, it was just Display Port causing problems again! Switching to DVI, I suddenly saw the system was already installing! DP is again not working in Catalina for me, although the update of WEG, AppleALC and Lilu had fixed it just a few days ago. So, I might just have missed the first phase on the screen, however, I only waited for about 5 minutes ...
Edit: Display port returned to working order in the OS after running Kext Utility once more.
Regarding Catalina, everything I checked worked well, including Sidecar!
One strange coincidence I just noticed (it is also on my Mojave Install, however ...):
I have no memory tab on the "About This Mac"-Screen. Yet, the full 128gb is working since applying the trick I learned from here.
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