For Android, I don't have a great answer for you. In theory you can install Fennec on F-Droid, version 57, the last version the last version of Firefox built by F-Droid that was based on the Fennec browser engine, but that has security vuln potential, increasingly so since its been a few years since Fennec -> Fenix switch.
For now, because I don't want to be hit by security vulns in the browser itself, I'm holding my nose and doing plain old Firefox mobile, leaving some of the tracking stuff blocked on my Pi-Hole, then letting my wireguard VPN ensure that even when I'm off Wi-Fi, my signal gets routed to my home connection so the Pi-Hole can stop some of the telemetry (but not all! some gets through no doubt).
Why am I holding my nose there? Because my planned next browser, Iceraven [1], is not yet out of alpha and published to F-Droid. I check every 3 months or so, once it is, that's where I'm going, because it's as close as I can get to Firefox Desktop, but runs on Android.