“When you use Signal, your data is stored in encrypted form on your devices. The only information that is stored on the Signal servers for each account is the phone number you registered with, the date and time you joined the service, and the date you last logged on.”
You’re more than welcome to register an account on canchat.org (my server).
And yes, as long as you enable OMEMO encryption, your server provider cannot read your encrypted messages.
https://providers.xmpp.net/ is a good resource for finding a provider (homeserver) as well.
That website is awesome! Exactly what I was looking for, thank you!