Idea to reach the cloud without actually having Internet -- using wi-fi cold-spots (for lack of a better term)

As some might recall, I am offline by choice. I still have to make periodic trips to public hotspots to send and fetch msgs, and to write this post herein for example.

I can theoretically improve on that using a Wi-Fi AP. I could run a webserver without Internet, which is only accessible to those in Wi-Fi range of my residence. They could connect via Wi-Fi and a captive portal kind of mechanism could force the traffic to a website that I run. The website could have a msg like:

“Please tell Alice@wherever that I like her idea and want to meet”

or something like:

“Please post to freecycle that I have an air fryer to give away if someone wants it”

Of course, that’s just a half-baked brainstorm to give an idea. That would not be a manual labor intensive procedure and a non-starter. But in principle I should be able to broadcast an encrypted personal msg to Alice and someone more connected should be able to run an app on their phone that automatically grabs their neighbor’s msgs and sends them.

I think there even already exists an Android app that exchanges msgs with other devices over wifi or bluetooth, which works without Internet. I forgot the name of it but I had the impression it was a system of its own that does not use other protocols like email or activitypub.

UPDATE: I need to look into some of these apps:

https://www.geckoandfly.com/22562/chat-without-internet-connection-mesh-network/