F-Droid is an installable catalogue of FOSS (Free and Open Source Software) applications for the Android platform. The client makes it easy to browse, install, and keep track of updates on your device.
This list obviously isn't everything, but there's a lot available. I kept it pretty broad although there's a ton of niche and specialized software available too.
OpenTracks - Keep track of how many steps you take throughout the day without a smart watch.
K9Mail - A privacy oriented mail client alternative to the Gmail app.
Diaguard - A diabetes diary app to track your blood sugar.
Drinkable - List a few ingredients and what liquor you have at home and it gives you a list of drinks you can make.
Newpipe - A YouTube client without ads.
Libretube - Another YouTube client without ads.
Blood Pressure Monitor - Same thing as the diabetes, but great if you have high blood pressure you need to track.
ChordReader 2 - Get guitar chords to learn how to play songs.
Fennic - A web browser based on Firefox that's privacy oriented.
Red Moon - Makes looking at your phone easier on your eyes at night.
Literally can't say enough good stuff about Newpipe.
Everything YouTube SHOULD be, this is. LISTEN TO A VIDEO IN THE BACKGROUND!!!!!11. Playback speed infinitely adjustable- good for lectures, interviews, etc. No ads. No bullshit.
Most of the apps of tibor kaputa. I really like the simple gallery. The simple dialer and simple contacts are also really good. Just clean default apps that do what they should.(adfree)
The UX for Mindustry sucks compared to something like Factorio, because it's really tough to do those controls on touch screen, but it's good enough. I've enjoyed it for the little I tried.
I prefer LibreTube because it doesn't look outdated and it uses Piped, so you never actually connect to the YouTube servers and you can synchronize your subscriptions and playlists
Thanks to US infrastructure I don't need yet another map just for public transport! Thanks US government for looking out for us little people! (I really don't think this is needed, but /s just in case.)
A lot of the utility is it having apps with similar capabilities but without the same kind of privacy invasions, and with better description of what anti-features an app has. So as far as 'the average user', I'd just say alternative apps (or even the same ones, if you're already using FOSS apps) to the same ones they'd use on Play Store, and a few of the games.