I just ran into this today. I had purchased an EVOO laptop from ebay or Walmart, for my Mom. It has 4GB of RAM, 64GB of eMMC, meets the requirements for TPM2.0 and Secure Boot. Only, apparently, the CPU, an Intel Celeron N3350 (Atom) was "unsupported".
So, in Win10, after the Win11 installer USB refused to install, I did the registry edit to allow unsupported CPUs and TPM, and the re-ran the installer. It eventually got to a screen, saying that I had to accept a disclaimer that basically MS wasn't reponsible for bug, crashes, or eventual self-destruction of the PC, should I choose to continue installation with an "unsupported" CPU. Big whoop.
So, it's installing, I'll probably know in an hour whether it "worked". Making sure that it gets updates, is another question entirely. If it doesn't, then I'll either have to remote in and manually install from MS catalog update site, or figure something out.