Of course, there are smartcards that could do this, you're just not allowed to have them. Plenty of smartcards nowadays are just flash and an ARM core which theoretically could be programmed arbitrarily. These tend to be used for credit cards, etc. Of course they might have acceleration units for specific algorithms like NIST ECDSA but I'd be surprised if Ed25519 couldn't be accommodated.

Unfortunately they're all NDAware, so they may as well not exist. ...But of course I've written about my extensive issues with the smartcard industry before.