I love it! Named formulas recently moved from experimental to preview. You can define them in the App's properties Formulas. That's how you can actually define constants now, instead of defining variables onStart of your app. You can then use these constants everywhere in your app, like in properties & fx
e.g.
uMail = User().Mail;
uFullName = User().Fullname;
uMngr = Office365.Users.ManagerV2(uMail);
(last one for those with 365 connectors. When using uMngr you have to add . followed by the actual value, like givenName, displayName and so on) Note, that I used the Mail constant, I set before, here)
Note the ; at end of each line - ;; for my fellow Germans 🙄
Another good thing is that it's real-time and you don't have to run the Apps' onStart to initialize variables any more ... as I said: I love it 😉