I stumbled across https://datatracker.ietf.org/doc/draft-ietf-tls-dtls13/ today. Looks like it's on its way now.

I took a stroll through the spec, and https://tools.ietf.org/html/draft-ietf-tls-dtls13-34#section-12 has the changed compared to DTLS v1.2. I'm copying it here for good meassure:

• New handshake pattern, which leads to a shorter message exchange
• Only AEAD ciphers are supported. Additional data calculation has
  been simplified.
• Removed support for weaker and older cryptographic algorithms
• HelloRetryRequest of TLS 1.3 used instead of HelloVerifyRequest
• More flexible ciphersuite negotiation
• New session resumption mechanism
• PSK authentication redefined
• New key derivation hierarchy utilizing a new key derivation
  construct
• Improved version negotiation
• Optimized record layer encoding and thereby its size
• Added CID functionality
• Sequence numbers are encrypted

Seems there's quite a bit of change. It might prove a fairly decent headache to support that.