Unfortunately the Qt demos all take 8-10 seconds to load on a phone for me and several of them fail with out of memory even on high end devices like a Pixel 4 XL. Certainly I'd expect a Pizza Ordering app to work on mobile (and to not show a flash style loading spinner for 10 seconds).

WT is doing all the logic server side so the client ends up being lighter weight and will work on more devices, and with better performance.