Turns out that the toggle switch isn’t going to help. I went out to the car, turned the ignition switch to ON, toggled the new switch, and the stereo has been drawing power for over two hours. So, installing the toggle was a waste of time and materials, and I’m back to pulling the fuse. Annoying!
Update on 26-Nov-2022: I re-wired the toggle switch to kill the fuse electrical connection, rather than the "ignition ON" wiring. Still an inconvenience every time I get into the car, but it seems to be a good work-around to just toggle a switch without having to constantly pull the radio fuse or killing my battery (had to buy a new one b/c drained too many times).