Are they enforceable?

I am no lawyer, but I don't expect that under EU work law anything done outside work can be forbidden in the work contract, in any member country.

The only issue I see from law point of view, is if whatever is being done, in terms of private projects, is related to knowledge acquired during the work activities, sometimes under NDA. Here yes, there can be issues.

Now if the projects are done in technology stacks or business domains completely different from what happens at work, then it isn't enforceable.

However I am no lawyer.

Which of the 52 states is that? Its probably closer to the CA i.e. it has to be related to the employers work not everying.