A Google Pixel with GrapheneOS is the best thing on the market for privacy and security.

GrapheneOS is a privacy and security-focused operating system, which is based on Android and retains full compatibility with Android apps. There are no Google services by default, but you can install Sandboxed Google Play services, which have much less access to your device, because they are running in the normal Android application sandbox, just like any other app you install, and can be removed at any time. GrapheneOS offers many other cool features, such as a network permission toggle, which lets you revoke internet access from any app (like e.g. the Google Camera app).

I'm glad you already know about F-Droid, because there are so many amazing apps there. After looking at your home screen and the apps you currently use, here are some quick recommendations from me:

• Before you start using F-Droid, add the IzzyOnDroid repoisitory, as it contains even more awesome apps that can't be found in the official repo
• Switch to a better F-Droid client, such as Droid-ify
• Revolution is the best IRC client I could find on F-Droid, it looks a little older (doesn't use the newest version of Material Design), but still works very well
• LibreTorrent is an amazing torrent client
• AntennaPod is IMO the best podcast app on Android
• The official Wikipedia app is available on F-Droid: https://f-droid.org/en/packages/org.wikipedia
• Element X is a new, rewritten version of the Element client (it's officially made by the Element team, and you can even try it out on iOS right now)
• Clock You is a good and modern looking clock/timer/stopwatch/alarm app
• There are a few Telegram apps on F-Droid. I have found Nekogram X to be the best. If you prefer the experience of the stock Telegram app, you can get Telegram-FOSS from F-Droid.
• For Signal, you can either use Signal-FOSS (requires a third-party repo), or an improved fork of the app called Molly (you can either get it from Accrescent, which is available in the GrapheneOS App Store), or by adding their custom F-Droid repo. Molly is officially recommended by the GrapheneOS project over the normal Signal app.
• The official GitHub app works just fine, but you can also try FOSS alternatives from F-Droid such as FastHub-Libre, or OctoDroid.

The other apps you mentioned in your post are not available on F-Droid, but I also have a few recommendations there:

• xManager for Spotify (it's a modded, patched version that removes ads)
• Aliucord for Discord (it removes some of the telemetry and tracking)
• Instagram and Steam can easily be downloaded from the Google Play Store. You can use Aurora Store, to download apps from Google Play without creating a Google Account.
• If you only need Steam for the authenticator, there is a way to get the verification codes in a FOSS TOTP authenticator like Aegis, without having to install the Steam app: https://help.ente.io/auth/migration-guides/steam/
• You can either use FFUpdate to download the Brave Browser, or use Obtainium to pull the APK from GitHub

Also check out Lawnchair launcher, since I at least find the stock launcher kinda lacking in features and UI/UX.

Feel free to ask me any further questions, either in this thread or via Lemmy DM