Any suggestions on what approach to take. Rooting and jail breaking seems over the top to serve compute power. Anybody got say an AIDE built app or similar that

Any suggestions on what approach to take. Rooting and jail breaking seems over the top to serve compute power. Anybody got say an AIDE built app or similar that works from Android 4 or something similar for iOS? I have a shoebox of old phones and tablets waiting for a project like this. I just don’t know where to start.