I was in the same situation as you, new cou, new mb, all ready for the update, no luck. Always this secure boot thing, but when i enabled it, pc wont boot into windows.
Turns out i was still on MBR, but nobody tells you this… after doing the reformat it was working to update.
Also make sure you download the window11 upgrade tool, the inbuilt update check might still say you are not qualified for w11.
It is really, really stupid how microsoft handles this w11 update path, if you are on MBR you are left alond to find out everything by yourself…. And i guess most peoples would just be stuck and never find out where the problem is…