On Ubuntu 20.04, snap apps install here:
/var/lib/snapd/desktop/applications
To fix UI scaling, I just add the following flag to each of the .desktop files for Electron apps in that folder
--force-device-scale-factor=1.2
before %U and this seems to work well for making the UI about 20% larger, which fixes the issues that I had been having on my 1080p screen on a 13" laptop
https://forum.snapcraft.io/t/overriding-desktop-files-on-ubuntu-snaps/6599/4
Add copies of *.desktop entries of snap apps in .local/share/applications directory
Turned out, symlinking isn't necessary
Just delete rofi drun, drun-desktop and run cache files
That will refresh rofi's cache