Why is there no 'ECDSA' version of 'DHE-RSA-CHACHA20-POLY1305'? So I was just checking my TLS cipherlist and noticed that there was a 'DSS' / DSA / ECDSA version of every RSA cipher available, except for DHE-RSA-CHACHA20-POLY1305.

Why is that?
The original cipher suites involving ECDH and ECDSA were all introduced together in RFC 4492.  They corresponded to existing cipher suites:

\begin{equation}
\begin{array}{rcl} 
  \text{DH_DSS} &amp;\longmapsto&amp; \text{ECDH_ECDSA} \\
  \text{DHE_DSS} &amp;\longmapsto&amp; \text{ECDHE_ECDSA} \\
  \text{DH_RSA} &amp;\longmapsto&amp; \text{ECDH_RSA} \\
  \text{DHE_RSA} &amp;\longmapsto&amp; \text{ECDHE_RSA} \\
  \text{DH_anon} &amp;\longmapsto&amp; \text{ECDH_anon}
\end{array}
\end{equation}

One might infer that the thinking was if you were going to take the plunge into the world of elliptic curves—recall in 2006 elliptic curve cryptography had (and to some extent still has) an undeserved reputation for being new and poorly understood in contrast to modular exponentiation systems in finite (quasi-)fields—then you might as well use ECDH key agreement, while you might keep your long-term RSA certificate because it was costly to buy a new one.  Doing it the other way around—buying an ECDSA certificate but using finite-field DH key agreement—would just be silly.

(Recall that this was also perhaps the heyday of the HTTPS certificate authority protection racket, before the browsers collectively imposed any semblance of regulation on it by the CAB Forum and long before Let's Encrypt rendered it obsolete.)

One might further infer that nobody bothered to break this pattern, because why would you want to do any more finite-field DH key agreement in this day and age anyway?