Is it possible to conditionally route pfBlockerng through a VPN for an interface?

[moutardefromdijon]

I have setup a Wireguard VPN tunnel, and can route an interface through it.

The problem is that if I use pfBlockerng's DNS while on that interface, then there is a DNS leak.
I could route all pfSense traffic through the VPN, but I don't want to because I don't need everything to go through the VPN all the time, and I would lose all Internet if the VPN goes down.
I want a single interface's DNS to be routed through a VPN (or to 9.9.9.9) and still benefit from pfblockerng's filter. Is this possible?

I think this can be done by setting the interface's DNS to another pfSense machine routed through that VPN interface, but buying another machine for this feels overkill and costs money.

Does anyone know how to solve this problem?

tldr: I want one interface DNS to benefit from being hidden by a VPN and to benefit from pfblockerng.