Okay, if we go with proprietary meaning strictly sole developer, and ignore that it has been developed with a community, first by mailing list, and now on Usenet [0]...
Gemini was first published roughly in 2019. At about three years old, what protocol has a standards board? It's too young.
It took C roughly 17 years to get a standards body.
It took Gopher three years to get the first RFC [1]. Was it a proprietary protocol? It was the same age as Gemini currently is.
[0] https://web.archive.org/web/20211026220037/https://lists.orb...