mDNS one way through vlan? Possible?

I finally thought I solved a small but irritating issue where I wanted to disable my Nest Mini from being able to be casted to. I created a separate guest wifi with a separate VLAN with internet access. The device was able to be included in my Google Home even though it is on a "separate" network.

Was happy at first and thought everything worked, could reach other devices and tell it to stream music on my other Chromecasts.

In the settings of the Nest Mini, you are able to select default speaker, here you can select a Speaker group. This works fine when they are on the same network, but when it is separated it cannot stream to speaker groups. They have to be available via mDNS.

I read a lot about this, and there seems to be avahi and mdns-repeater which helps with this. But from what I understand this will enable the communication both ways, I only want the Nest Mini to reach my speaker groups, but not my regular network to see the Nest Mini. Is it possible to have a one way communication for this?

Thank you!

Try this.