There's nothing illegal about these as long as you're not doing anything illegal. It's not illegal to take pictures of people in places where there's no expectation of privacy.
I live in Japan and see Chinese livestreamers walking around all the time. Stores are allowed to refuse their business, but it's not illegal to record others in public. Whether this counts as a hidden camera isn't up to me, but since it has a glowing LED indicating when it's recording I wouldn't think it would be a problem.
