Android:

• Nexdns.io^1 - Open source DNS provider with DNSSEC and over TLS. Then can also block ads at the DNS level. I don't actually use the app, I apply it at the system level with the "private DNS" settings.
• Bitwarden^2 - Open Source password manager with Yubikey auth and stores TOTP.
• Imagepipe^3 - Quickly and easily strip exif data from image (open source too).
• Markor^4 - Used to make local notes of things I don't want shared over a cloud or google connection. Just a .md note.
• Wireguard^5 - Have my own VPN setup for when i'm on public wifi, also allows me to access my server/applications remotely.
• URLCheck^6 - This app is fantastic, intercepts links to remove tracking parameters, unshorten them or even scan them with a virustotal API. I also use it to redirect twitter to nitter or apply a paywall remover.

Imma add TrackerControl to those already mentioned in other comments.

Edit: cosmetic change

• Mull browser with uBO
• Duckduckgo for tracking protection
• Proton email

Rethink DNS

@badgrandpa

Blokada

Bitwarden

ublock origin

Firefox, Signal, KeepassXC (DX), Tor, Proton Mail, OpenBoard, microG, Joplin.