Here is a short list.
Pc: Cachyos(Preformant linux distro based on arch),Cinnamon (fork of Gnome 3),Librewolf (web browser)
Android phone:F-Droid(Appstore),Clipious(YouTube client but network is nonfree),aurora store(replaced Google play store with this and network nonfree),Iceraven (Web browser,Can be hardened as much as mull.),
Cross platform: Localsend(Airdrop for any device),Vlc media player
Yeah that’s it,here is my major apps I use

Matrix (element on mobile, cinny on pc), materialious (linux app for invidious, alternative yt frontend), gzdoom (foss engine for doom & mods), luanti (a minecraft-like engine for playing minigames and shit), zen browser (firefox fork with a pretty skin), xfce as desktop environment, wine for playing windows games

Android Custom ROM itself

-Adaway -App Manager -Audile -Audio Recorder -Aurora Store -BiglyBT -BitmaskVPN -Bitwarden -Calyx VPN -Capy Reader -Cromite -De-Bloater (i translated it to hungarian) -easyNotes -eduVPN -Eternity -F-droid -Android Files -Android Recorder -FlorisBoard -Android FM Radio -freeDictionary (Owl) (i also translated the menu to hungarian) -FTPClient -FUTO Keyboard -Gadgetbridge -Android Gallery -Android Game Space -HeliBoard -Human Benchmark -Breezy Weather -Image Tools -Invizible Pro -Jerboa -Lagrange -LavSeeker -Magisk -microG -Namida Music Player -Fossify Calendar -Fossify Contacts -Next Player -Obtainium -OCR -Odyssee -OnionShare -OpenCamera -OpenVideoEditor -Android Clock -Forkgram -Organic Maps -Orion Viewer -OSS Document Scanner -Pachli -QR Scanner -Racoon -Revenge Discord Client -Root verifier -SD Maid -Seal -Setter -Shitter -SlimSocial -Spotube -StrongSwanVPN -NumberHub Calculator (i also translated this to hungarian) -Fossify Phone -Termux -Thunder -TranslateYou -UPnP Explorer -Fossify Messages -Vernet -ViperFX Material UI -Voyager -Warden -WikiReader -Xtra

And this is only my phone…

On my laptop:

• Void Linux
• GNOME (desktop environment)
• gThumb (image viewer that can do simple edits)
• Firefox (the famous web browser)
  • uBlock Origin (content blocker that blocks ads, trackers, etc. out of the box)
  • SponsorBlock (automatically skips sponsor segments in YouTube videos)
• Betterbird (fork of the Thunderbird email client, with various QoL tweaks)
• GIMP (image editor)
• Kdenlive (video editor)
• virt-manager (manage QEMU virtual machines)
• Celluloid (media player)
• yt-dlp (command-line utility for downloading YouTube videos, and the basis of some graphical apps as well)
• Bottles (if you want to use Wine to run Windows apps, without too many headaches)
• Foliate (.epub ebook reader)
• OBS (for screen recording and livestreaming)
• Code - OSS (code editor, “clean” version of Visual Studio Code without “Microsoft-specific customizations”)
• Tenacity (fork of the Audacity audio editor without opt-out telemetry)

On my Android phone:

• F-Droid (app store with FOSS apps only)
• Obtainium (auto-updater for apps hosted on GitHub, GitLab, etc.)
• Heliboard (simple keyboard app)
• Material Files (file manager)
• Metro (local music library player)
• Iceraven (Firefox fork with a few tweaks)
• Voyager (mobile client for Lemmy, similar to the obsolete Reddit clients Apollo and Slide)
• Fedilab (client for Mastodon and similar Fediverse services)
• Termux (run Linux CLI applications on Android)
• Thunderbird for Android (simple email client for Android and the successor to K-9 Mail)
• MJ PDF Reader
• Binary Eye (simple QR code scanner)

Cross-platform:

• LocalSend (simple file transfer between devices on the same network)
• Bitwarden client apps (to manage passwords. I use the Vaultwarden instance @ tchncs.de)
• Mullvad VPN client

If we can count FOSS modifications of proprietary apps:

• YouTube Revanced (the official YouTube app, but you don’t get ads, you can play videos in the background, you get SponsorBlock, etc.) (follow this guide for auto-updates)
• Vesktop (desktop client for Discord, has Vencord preinstalled and supports Linux screen sharing)
• Prism Launcher (Minecraft: Java Edition launcher that allows you to easily manage different “instances” of the game. Good for playing with different mods and/or versions)
• Fabulously Optimized (modpack for Minecraft: Java Edition, that improves performance and adds some minor QoL features)

addendum: I’d like to use Matrix (via the Element client) and Signal more, but most of the people I know are on Discord and WhatsApp instead.

Dosbox (magic dosbox for android) Scummvm (scummvm for android) UnCiv Obsidian Obtainium URLCheck