Installation
I installed Qubes 4.0.1 on a 64GB SanDisk Ultra 3.0 USB (not the hard drive), and it was easy. I enabled legacy boot and disabled secure boot. There was no need for UEFI troubleshooting.
I haven't gotten a chance to test the features. The trackpad didn't seem to work during installation, but after installation, the built-in keyboard and trackpad both worked.
The USB Qubes were not configurable on the start-up after installation. It took about an hour for installation and configuration onto the USB.
On start-up and shut-down, I saw:
[FAILED] Failed to start Load Kernel Modules.
See 'systemctl status systemd-modules-load.service' for details.
Link to specs (also attached as PDF):
The processor was an i7-8565U.