At the moment no queries unless you sign with a nostr key with credits.

At the beginning it was totally open and in 2 weeks since the launch I got people abusing it, so I had to gate it somehow.

Yes it could be zap based but I would still have to check if your key has zapped vertex, so still sign in.

I could accept ecash in the request, but then your user would have to have a wallet, which imo is more selective than a sign in