

You can actually pet grown hedgehogs, I think if they are happy the needles are not pointing upwards, but I might be wrong about it.
Source: visited a hedgehog café in Tokyo like 10 years ago, did pet hedgehogs.
Edit: rereading what you wrote I realise you maybe didn’t imply that an adult hedgehog cannot be petted…
It wasn’t great, but interesting. Definitely pokey still but maybe the hedgehogs weren’t too happy being handled. I also read somewhere they can be quite big assholes as pets, but no idea if its true.
Edit, sorry forgot the rating. Maybe 4 of 10.