Seeing recent news from Belarus, where the gov. shut down the internet, I was wondering if it's possible to have a decentralized mesh network using the wifi of cellphones and homes to communicate with each other. Does this exist?

So due to rigged elections, civil unrest has arisen in Belarus, and the government has shut down internet access to limit communication between citizens.

I was wondering if someone has created a solution for problems like this, where you can repurpose the wifi routers, computers and cellphones to create a decentralized network, to allow people to communicate between each other in an encrypted way, and access the internet if some of the nodes have access to the outside internet network.

I'm interested to see the answer