Its fairly new, as in June/July 2025, so I imagine they want to iron out the bugs before letting opening the floodgates.

If you check dns0.eu (free dns service for EU provided by the company behind NextDNS), it says they’ve closed down, and refer to DNS4EU or NextDNS.

As for what the different categories cover, they have the block lists they use linked “somewhere” on their page.