And for reference, this is how a desktop file generated by chromium looks like (note that the Exec line is incorrect as it points to the chromium binary, and would result in it being run unconfined):
#!/usr/bin/env xdg-open
[Desktop Entry]
Version=1.0
Terminal=false
Type=Application
Name=Snapcraft forum
Exec=/snap/chromium/887/usr/lib/chromium-browser/chrome --profile-directory=Default --app-id=fadliobngcdalcjhmgmngaocgindcomi
Icon=chrome-fadliobngcdalcjhmgmngaocgindcomi-Default
StartupWMClass=crx_fadliobngcdalcjhmgmngaocgindcomi