I have Oculus Quest 2 with update v26 . I just installed Sidequest following the instructions on their site. I uploaded a game successfully. However I cannot find it in the Quest 2 headset. The only "unknown sources" I found was under storage and it showed the game and size . It cannot be launched from there.
You can find the Unknown Sources installs from the Apps menu, using the drop-down at the top right. See this screenshot (source: https://www.vrtourviewer.com/docs/install-vr-tourviewer-on-oculus-quest/)
Thanks all for the advice. I found it!. I had to select the apps icon at bottom of the home screen menu. Then at the top right there is an "All Apps" selection icon with a drop down list . When I scrolled down the list I found the "unknown Sources" link at the very bottom. However the strange thing was that it was not even there when I had just finished installing side quest. Only when I had shut down everything and booted up the headset the very next day viola - it was there!