Most good VPN providers will have their own native app which you can install on Android. If not, then there are apps such as OpenVPN or WireGuard which will let you connect to any VPN service, and again, most good VPN providers will provide pre-made configuration files to use with these.

Firefox for mobile is just as powerful as their desktop version. You can still access the necessary privacy and security add-ons such as HTTPS Everywhere, uBlock Origin, and Privacy Badger, and you can also still access the about:config to apply necessary security/privacy tweaks.

Tor browser is obviously a good choice, but you can also use an app called Orbot, which will route all your internet traffic (from any browser or app) through the Tor network.