The procedure is much hassle free than it looks. Keeping the secure boot on enrolled is a good practice. I read recently that Fedora was approving the sign automatically to be part of the gnome-software. So things may become even easier soon.
For Fedora you can follow the RPM Fusion documentation or have a look to this guide
Maybe a laptop with a very good CPU and an eGPU? You can get it from Aliexpress.
Very good write up. If I not agree with all, I probably agree with most that is in here. On the DE section, I think we should help drive the beginner choice. In the recent past, KDE and Gnome were the early adopters of Wayland and the ones introducing the new features. They are also the choice of most distros. Therefore, I’d recommend one of those two.
I’d open a new section worth of scrutinies, dedicated about security. I believe it may worth advising that as a criteria of selection is recommended to not use distros that freezes regular releases for more than 1 year in desktop installations. Like is explained here. At least in your first distro selection. Advise about restricting privileged access with SELinux or AppArmor. Perhaps, also add a note about secure boot as well and some guide of how to harden your installation, Madaidans, Privacy Tweaks, PrivSec and PrivacyGuides.
If there is one thing to criticize is the need to install Gnome Software. I’d prefer that this was available in the KDE Discover.