For the search you need to know the instance someone is on, I have had the issue of knowing someone is using mastodon or compatible service and even their username, but not the inatance they’re on because I don’t know them personally.
The one largeish local instance that shut down recently had the covenant in the server description, until one day it wasn’t and the server shut down in a month.
Switching servers leaves a lot behind. You can only force your followers to be switched to the new account and export and reimport your own follows. But everything you had posted gets left behind. You can download the whole archive for yourself, but can not currently republish it from the new account.
Still it’s the best social media I have used this far and am expecting it became garbage in a few years now that it is getting popular, because they always do. But let’s have fun while it lasts.