https://www.apkmirror.com/apk/mozilla/firefox-fenix/firefox-fenix-nightly-200923-1442-release/firefox-nightly-nightly-200923-1442-4-android-apk-download/
Just downloaded the Firefox Nightly for Developers Nightly 200923 14:42 (arm-v7a) (nodpi) APK from @APKMirror