rg1. I agree. A mesh over the top of the gutter is game over for future cleaning.
But I think the gutter hedgehog is slightly different - a sort of long cylindrical brush which sits in the gutter and stops leaves etc settling inside the gutter whilst allowing the water to flow.
I've got no experience of them but somebody is making them, hence some people must be buying them. Can imagine them getting very messy with leaf mould and moss etc.
At the end of the day I don't think anyone has really found the perfect alternative to having the gutters cleaned (hopefully by me
)