i've not used it in a while but https://mastodon.social/@xero
i'm also on some private nodes https://slime.global/@xero

you use private nodes b/c they have less load, cool domains, and usually custom css.

the admins decide what nodes will be publicly displayed on the federated timeline of that instance. but you can follow (and see posts) from anyone on any node. you just need to use their full instance (domain) and username.