for those like me who cannot install alternative android forks on their phone because the phone in question is thoroughly unrootable, I would recommend downloading anyapk on your phone while you still can. In their own words:
anyapk is a lightweight Android application installer that bypasses Google's developer verification requirements by using local ADB (Android Debug Bridge) connections. Smoothly install any APK file on your device without restrictions, gatekeepers, or corporate approval.
If you're reading this after Google's lockdown date and are unable to install anyapk the regular way, there is a method outlined on the github linked above which tells you how to install anyapk on your phone by plugging it into a computer with ADB installed on it. Once you have anyapk on your phone, you will not have to do that ever again (unless you delete anyapk off your phone)