Announcement-only channels

[n2aws]

Apologies if this has been discussed before. (I searched but didn't see anything relevant.)

Request:
Add an ability for multiple nodes to receive messages, but not reply to them. ie, a channel for announcements, only.

Use-case:
Local Emergency operations center (EoC) has expressed an interest in finding better ways to communicate information to the public after natural disasters (we're in a hurricane-prone area, and getting info to the public during multiple day power outages is a constant struggle)
Meshtastic was discussed, but the primary problem is: After the EoC were to broadcast a message (where first aid stations are located, where water and food resources are available, which shelters are available and have capacity, etc) anyone can respond. This will lead to confusion, chaos, and noise.

If there was an announcement only channel capability, we could let the general public add the channel to their devices so they can receive messages. However, only "authorized" nodes would be able to send to the channel reducing the amount of noise confusion via this method.

Essentially, I'm thinking of something almost opposite of public/private keypairs, where anyone can "decrypt" but only a few could "encrypt" the messages.