I'll try to keep this to lesser known apps:

• Catima (saves barcodes for gift cards, gym memberships, etc so you don't have to worry about the physical card)

• Cofi (nice timer for active guidance through coffee brewing recipes)

• 10,000 Sentences (a language practicing app that doesn't have a mildly threatening owl 😉)

• OSMAnd+ Mapillary, Overlay Maps, and 3D Features (seriously, the best. I only use Google maps to get around traffic these days since, unfortunately, Magic Earth doesn't work very well in my area)

• Obtanium (as a gateway to lesser known software, no shipping to an app store required!)

• RethinkDNS (an absolutely amazing piece of software that gives you fine-grained control of the domains your apps are talking to. A bit of a battery sync but it's been a game changer for me. On my GrapheneOS setup I use it in the Google sandbox to reduce the amount of data scraping servers my Google apps can talk to)