Does XChaCha20 exist with similar properties to XSalsa20? Does XChaCha20 (built from ChaCha20 just like XSalsa20 is built from Salsa20) exist and have XSalsa20's desirable properties?
Unfortunately, there is no specification for XChaCha20. But several implementations provide a HChaCha20 function, built the same way as HSalsa20.

XChaCha20 can be built with HChaCha20 + ChaCha20, and the security proof is similar to the one for XSalsa20.

The Libsodium documentation has a section on HChaCha20, which includes a code snippet to build XChaCha20 out of it.