Hypothetically, I imagine community group chats, whose members also text warnings to other locals not in the chat, and those people then spread the word further. When agents are seen lurking around town, someone sends the word out, and maybe people can even gather in person and follow the agents to warn passersby, film any arrests, remind people of their rights, and protest.
What’s legal and what’s not?
The law doesn’t matter in the grand scheme of things.
Its better than doing nothing.
Its better than doing nothing.
This thing you’re describing is, at its core, a basic community defense thing. Everybody has a few phone numbers they can call/text with “news” when needed, no one person has everybody’s number and no one person is responsible for contacting everybody. Letting people in the area know there are “strangers behaving strangely” or “hey, do you know what’s going on with all the cops going door to door?” is not outright a crime.
Its not your job to know the immigration status of everybody around you or their family or to remember any conversation you may/may not have had with a person.