@popey
I never had a real reason to look at other distros with Gnome shell before. Earlier Ubuntu had a DE no one had.
Anyway, checking standalone apps, such as Chromium, that I took out of the Chromium snap in Fedora 31 beta. I just copied the whole folder chromium-browser there and ran,
$ time ~/chromium-browser/chrome
The result,
real 0m4.541s
user 0m3.058s
sys 0m1.146s
In Ubuntu it was,
real 0m5.087s
user 0m6.032s
sys 0m1.318s
Just took the folder and put in Fedora 31 Beta. That folder is ~1/3 of the size of the Chromium snap in terms of MBs (607.3 MB snap, to 237.2 MB) . Just as portable!
Fedora installs Chromium browser normally, and the strange thing is it started slower than the one I took there.
$ time chromium-browser
gave,
real 0m14.429s
user 0m12.534s
sys 0m2.190s
Note: Of course, I can take the whole folder /usr/lib64/chromium-browser and place it anywhere and click on the executive file, and Chromium would start, also placed in Ubuntu. That one is also quite portable.