I had a little radio like that years ago, branded "Precor" IIRC. Don't remember where I bought it, though; probably at a discount store, as I didn't pay that much for it. Did not realize, however, that it was a rebadged Panasonic.
Why would this be the "Model T" of portable radios?
The circuit was probably the same as any other pocket portable of its time (unless it had fewer than six transistors). Not high-fidelity or a DX machine by any means but I'm sure these must have been a favorite of kids and teenagers, judging by their popularity when they were new.