I introduced kbin to someone today who asked what the fediverse was. I answered for them of course, but it made me realize that the concept is still technobabble for most people. The average joe probably doesn’t care or notice that server A is really talking to server B. Just have them find out on their own and if a mass migration does need to happen from A to B, just make a standard announcement.
You don’t have access to the ones which refuse to federate (for example, because they will only federate with instances that accept the same Code of Conduct).