Allow content and interaction to flow between the federated instances

Someone with way more knowledge about this subject than I can correct me if I'm wrong, but from what I gathered it's good to think of these things like this:

Instances (kbing, lemmy, mastadon,etc) are like Cities. They can function interdependently but do better by being connected (federated) to other cities. If, for example you are like me, and despise a certain city, your city can choose not to connect with that city, but doing so means your citizens won't be able to see/do anything with that city.

i'm from australia. australia is a federation. this country is made up of six states and a number of territories. the six states are all still legally distinct entities with their own individual laws that do not impact residents of other states. to be able to be part of a larger country tho, our different states need to comply to another, higher set of rules that are decided by our federal government. it is theoretically (but not legally) possible for a state to be ejected or to leave the federation in which case they won't have to comply to the federation-wide rules any more. for example, the country of New Zealand has had a standing invitation to join the australian federation ever since colonies on the australian mainland started talking about declaring statehood and then joining up in a federation, but those smart bastards have always told us where to go and where to tie our horse up when we get there. the fact that they've literally always had better conditions (eg women being allowed to vote and own land) might have something to do with it