Presently? Hardly at all. It is interesting that a private Corp is even seriously playing with building a decentralized platform, I guess.
The files are out there to host your own server but from the short look I took it’s pretty involved. Most people with the knowledge and interest to host their own twitter-like server have probably already started a mastodon instance.
It’s also not, like, unattainable
But it’s definitely well beyond what any hobbyist is going to set up in a whim