I personally tend to own two Phones. One all-day carry GrapheneOS device (Pixel 8) and an older WiFi and at home only iPhone for all payment and ensurance stuff.

This is inconvenient in some ways, but at least it is sort of privacy as good as it gets while still being able to run official apps when I need them at home.

To de-google the phone, I use F-Droid as primary App store, Aurora as fallback for non-f-droid Apps and as a last resort Obtainium to install Apps that are not in these stores.

The only google App I really "need" (kind of) is the Camera App, which is sandboxed via GrapheneOS Storage Spaces and without Network permission (why would a camera need internet?).

To backup my phone, I use the integrated GrapheneOS Solution (seedvault!?) for storage and apps, immich for Photos and MyPhoneExplorer for Contacts.

Sometimes it is a bit hard to find good apps for specific purposes, so for everyone interested, here is a list of Apps that I personally use or have used.

  Newpipe - Youtube Client
  Audiobookshelf - Audiobooks
  Voice (PaulWoitaschek) - Local Audiobook Player
  Substreamer - Music
  DSub - Music (alternative)
  VLC - Video-Player
  Organic Maps - Google Maps alternative (not as good)
  PDF Doc Scanner - Open Source Document Scanner
  Wireguard - VPN
  Immich - Photo Backup / Viewer
  LocalSend - File Transfer
  K9 Mail / FairMail - Email Client
  KOReader - Ebooks
  Binary Eye - QRCodes and Barcodes
  Pure Todo - Self hosted PWA PHP Todo List 
  Signal - Messenger
  Open Camera - Open Source Camera App

Some other FOSS apps I use daily:

Aegis - 2FA (https://github.com/beemdevelopment/Aegis)

Breezy Weather - A very good looking weather app (https://github.com/breezy-weather/breezy-weather)

OnlyOffice Documents - MS Office suite replacement (https://github.com/ONLYOFFICE/documents-app-android)

Fossify Calendar (https://github.com/FossifyOrg/Calendar)

Fossify Messages (https://github.com/FossifyOrg/Messages)

Aves - Local gallery with great organization (https://github.com/deckerst/aves)

Termux - Terminal emulator (https://github.com/termux/termux-app/)

Unexpected Keyboard - A unique keyboard that pairs nicely with Termux (https://github.com/Julow/Unexpected-Keyboard)

WG Tunnel - WireGuard client (https://github.com/wgtunnel/wgtunnel)

These are all easily installed through Obtainium: https://obtainium.imranr.dev/

I like Organic Maps because it isn't full of the social things. Every time I open Google Maps it shows that card at the bottom with "what's popular in your area", full of pictures of people's breakfasts and other nonsense. Organic Maps is free of this noise.

Also, the desktop client on Linux is quite useful.

Alternatives for Windows etc. are Cruiser Maps, a Java application (and also available as an Android app).

Voice audiobook player is so nice and simple, a pleasure to use

Grayjay is another good YouTube (and other streaming platform) client made by the company that owns Immich