This list is not advice on what you should do, just some power-user stuff I enjoy or have enjoyed doing.
There are risks to using any of these, especially if you blindly set them up with permissions without thinking about them.
For one, Android can natively store the notification history, but deletes anything older than 24 hours.
Notifications Recovery does not auto-delete its history, and can therefore be a nightmare if e.g. the police accesses it. Personally, I used to blacklist all sensitive (e.g. email and chat) apps in it and was okay with that, but now i'm not using it anymore.
Similarly, CubeACR is made to record calls. If you store them on your phone, then anyone who gets access to your phone unlocked (e.g. police) will get them too.
- (as mentioned) KDE Connect and Syncthing are great
- RoundSync to connect to any cloud storage (basically a nice UI for rclone)
- Termux to get a terminal (only works on Owner Profile)
- Custom notifications via ntfy
- Unified-Push for compatible apps c.f. https://unifiedpush.org/users/apps/
- Private Spaces can bring a lot of privacy and functionality (can get multiple accounts for single-account apps)
- Work Profiles (typically via Shelter/Insular)
- Phone automation (e.g. via Tasker/Automate/MacroDroid/etc)
- Secondary user profiles
- FairEmail (to replace your email clients like Gmail and Outlook)
- System UI Tuner to customize the Status Bar and e.g. display seconds on the clock
- Super Status Bar to e.g. control brightness by swiping on the status bar
- CubeACR to auto-record calls (phone calls and VOIP (Signal, Whatsapp,etc) calls)
- LinkSheet to customize behaviour when opening links (and possibly preprocess links)
- NativeAlpha to create customizable PWAs for any website and backup these PWAs
- Nova a very customizable launcher
- Notifications Recovery to store and search notifications
- (with a warning, maybe don't start there, this brings some downsides) Device-Owner c.f. https://discuss.grapheneos.org/d/35124-any-single-tap-ways-to-toggle-disableenable-apps/8 A major upside is the ability to make Android enable its native "Wipe after X bad unlock attempts" feature similar to iOS. Other apps that do the same need to be running and therefore do not work after a reboot (i.e. BFU). AFAIK, a Device-Owner is the only way to make a "Wipe after X bad unlock attempts" feature work BFU.