Is there a way to apply specific Listener/Network Filters to Envoy instances managed by Contour Gateway Provisioner?

[hbobenicio]

Context

1. I'm using Contour Gateway Provisioner (dynamic provisioning) and Gateway API with k8s. Latest versions
2. I'm trying to set a particular Filter to Envoy's managed by it.
3. My use case is routing and proxying North/South traffic from downstream postgres clients (outside k8s) to upstream postgres servers (inside k8s).
4. I'm trying to Terminate TLS connections with Gateway API's using TLSRoutes.
5. The problem is that Postgres protocol requires a specific message exchange between client and server right after the TCP Handshake and right before the TLS Handshake in order to support session encryption.

Question

How can I set a specific Listener or Network Filter to Envoy's provisioned by Contour Gateway Provisioner (hopefully [PostgresProxy](envoyproxy/envoy#10942 in my case).

Thanks anyone in advance