[deleted] There are a lot of everyday solutions that either don't require network access, can be self-hosted, or that are at least fully open source so that transparency is provided. The entire suite of Simple Mobile Tools, Signal, Jabber, Syncthing, DAVx⁵, Mastadon, Matrix, K-9 Mail, KeepassDX, Collabora Office, and Infinity for Reddit all fall into this category but there are dozens more. Even many Google apps can be used without Play or network permissions, if you choose to use them, including Gboard, Camera, Photos, and Gallery.
At some point, I plan to post a comprehensive list of the apps I use daily, to help others get an idea of the options that are available once you step away from mainstream providers.