@Alain This featute isn't in UT/Lomiri yet. Simplest way is to make something like a home screen app and there are some that exists already like Launcher Modular. Not sure they have app groups though. You can contribute to them if you don't want to make your own. However, they obviously act like a normal app. Best you can do is pin it to the Launcher for easy access.
Or you can contribute to Lomiri and implement it in the App drawer which definitely needs some love
There's even a bounty for it so there's money to get
