We’ve always had the New App from Data option, which keeps all of your relations and computed columns. There is nothing on the data side that you should have to be rebuild.
Yes you’d still have to rebuild the screens, but I honestly I can’t see how Glide could reliably convert a classic app to a new app without some kind of manual work required by us after the fact. There’s just enough differences between the two that I feel a one-to-one conversion would be difficult or inaccurate. Even if Glide does create a full conversion tool, I’d maybe try it once, but most likely would never use it. I’d rather rebuild the screens myself so I know how everything is put together, it looks the way I want it to look, and there aren’t any surprises.