I don’t know anything about cryptography. Would this have been useful for spies? Please tell me spies somewhere in the past were sending and receiving messages on a Barbie typewriter.
And for those that are unaware, substitution ciphers have been unsecure for over a millennium now. So relying on nobody guessing you used a Barbie typewriter isn't an option either.
Not in the slightest. If you would rank all types of encryption by strength, this would be one of the weakest ones, right between writing the text upside down and choosing a custom font.
Enigma is not that easy to crack, even today. I wouldn't compare it to a simple substitution cipher as to laymen that sounds like it was some pretty good shit even if it wasn't as good as Enigma.