Some of the stuff I use for mostly Google-Free Android

I'll throw in another page to avoid rambling on about my history with smartphones.

Operating Systems/ROMs

The most common way people have run Google-Free Android in the past has been CyanogenMod and it's spiritual successor, LineageOS. LineageOS is a community maintained OS built from the Android Open Source Project (AOSP) code, with several additions added over time. In the very early days (as in the first Android phone, the HTC G1) Google told the CyanogenMod project it could not distribute the proprietary Google Apps, including things like the Maps, Android Market (now known as the Google Play Store), Gmail, and YouTube. The response was that Cyanogen put out an OS that was free of this software, and seprately there was a release of the Google Apps that could be applied. What at the time was merely a workaround led to what is now one of the primary uses of Lineage OS, the ability to run Android without Google's software.

Lineage OS and some of it's derivatives like OmniROM are a great option, but their primary focus is more along the lines of providing customization and extending the usable life of devices that are no longer getting offical OEM software upgrades. There are now a couple of projects that are designed with privacy and security as a primary goal. These systems are designed to install an AOSP system without Google Apps, and then lock the bootloader to make use of some of the hardware security measures Google has put in place on their Pixel phones, including the Titan M Chip.

Blah, blah, I might update this more at some point. But my main idea here was to list some of the software.
Some Sources
Music and Audio Players
Social Media
These are typically either just wrappers for the website for convenience, or privacy focused apps
Ebook Readers
Un-Productivity (Games)
File Manager
Photo and Video