I'm not sure who is pushing #GlobalSwitchDay probably won't amount to anything, some of these platforms are certainly not ready a massive migration. The #RedditMigration was rough enough on Lemmy, it actually murdered #Kbin; #loops #PeerTube and #Friendica don't have nearly enough well-maintained instances to support any sort of massive migration. And Signal, well its better than WhatsApp, and its mostly Free Software, but it doesn't really align with all of the others that are, or at least intend to be in the case of Loops, federated services based on ActivityPub.
Wow, reddit migration killed kbin? Did all of them just flocked to a single server?
It was more like, the single kbin dev couldn't deal with the stress of maintaining and scaling the software, so he just quit. Mbin was forked from kbin, though, and seems to be doing fine.