Use navigation bar

[Jomyy]

Make one nav item to discover new apps one to manage installed apps and one to do something else (to be material guidline conform)

[k2helix]

Maybe something like in the official app?

In the official F-droid app there's one tab for categories which has different categories in which you can have a look.

It also has a tab for the latest which could work as what you suggested for discovering.

[vertigo220]

I'm a bit confused on this, because it's already this way: "Explore" tab for discovering new apps, "Installed" tab for managing installed ones, and "Updates" tab for updates. Unless you mean putting them at the bottom, in which case I personally prefer tabs and such at the top vs the bottom. I also caution against strictly following Google's UI guidelines, since they're not always the best way of doing things (and often aren't), Google themselves doesn't always follow their own guidelines, and they tend to change them every so often, making more work for everyone to keep up. Plus, yes Droid-ify is running on Android, a Google platform, but the whole point of it is to use something non-Google. IMO, it's much more important to find and use a UI that makes sense, works well, and looks good than to simply follow a set of guidelines that may or may not actually be good just because they're there. And one of the reasons I use Droid-ify over F-Droid is because I think its UI is much better.