I'm curious, what's your use-case since you say you can't self-host.

Where do you need to sync to? What kind of devices do you need sync between? Do you need to share some credentials between people?

Knowing these things will help us answer the question. For example, you don't need some "server" to host Vault Warden - that can run on your own PC/laptop. But there are other ways to do this like Keepass (already mentioned).