@UtterDisbelief,
@Feartech,
@Edhawk and many other into several threads :
Thanks a lot for your help and advises, since now my Ventura install works quite fine.
As suggested several times, the culprit was the USB mapping, and I do not fully understand why it was such a pain.
The workaround was indeed to clone the EFI to a bare USB stick while the "Install macOS Ventura" was cloned to a spare APFS empty SSD volume. After many EFI and config.plist cleanups and several reboots, it finally worked.
So once more, Many Thanks.
However, one enigma remains and puzzles me : I read somewhere the on a given hardware setup, the USBMap.kext, apart from the SMBIOS target, should remain the same. In my case, SMBIOS is both for Catalina and Ventura, the same iMac20,2. So far so good.
But, Hackintool provides me with 2 different pictures of the situation : in black, Catalina case, while on the white picture is the Ventura one. The number of activated ports is juste fine for Cata, while it is wrong for Ventura.
How comes ? Something I understand wrongly may be ? A hidden parameter ?
Thanks in advance for your hints, Regards, G.