Currently Let’s Encrypt does not make this distinction or use this terminology this way, but we’re happy to issue such certificates and do so every day.
Looking at the Certificate Transparency logs, an example that we issued recently is
X509v3 Subject Alternative Name:
This was issued using our normal procedures, policies, and technology and nobody had to do anything out-of-the-ordinary to request this certificate. Overall, I’d casually guess that about 10% of our certificates are UCC certificates under this definition, though I haven’t investigated this carefully and the correct number could be quite a bit higher or lower.
Let’s Encrypt currently doesn’t issue wildcard certificates at all, but is planning to do so starting in January:
I’d still agree with what I said a year ago: