This is a step-by-step that seemed to work for me (dated March 2023).
npm install -g nativefier
(see https://github.com/nativefier/nativefier)- Move
icon.icns
into your user directory - Within your user directory, run
nativefier 'https://docs.google.com/spreadsheets' --user-agent firefox --icon icon.icns --name 'Google Sheets' --honest
- Open generated folder and move Google Sheets application to your Applications folder
- Open it
- Open Activity Monitor, right-click on columns and ensure Kind is selected
- Search for Google Sheets to double check Kind=Apple. If yes, this is a Universal App ✅