Well, when a country invades a region, that region becomes part of their country, although residents retain power for regional elections, congress elections are restricted to citizens of invading country. So , no citizenship is granted but there are some "colonial" rights such as mayor election and using currencies of both countries in the region.

And apart from communication channels they will form (chatroom, forum, discord etc) , there will be a "shoutbox" system similar to Twitter's , not sure if "national feed" makes sense. I doubt a general chatroom filled with tens/hundreds of people is manageable at all :)