There is undoubtedly a ton of socialist history regarding the promulgation and study of Esperanto.
https://en.prolewiki.org/wiki/Esperanto
It does not seem like it is nearly as popular as it once was, but there are examples of it being used and even celebrated in Cuba, China, and the DPRK.
I adore the idea of a lingua universalis. I am also aware of many of the criticisms of Esperanto, from its ostensible Eurocentricity to its difficulty with escaping unnecessarily gendered language.
Is there much use in learning it, outside of personal interest or as a hobby? Do you think that there are Esperantist movements large enough to justify learning it? Enough speakers?
Globasa looks like neat alternative "universal language" project that's doing a least a little better than others at avoiding eurocentrism. Every world language family has to be represented.
Looking at a few of the sample sentences I see of the language, it would be a great language to use in a fictional setting. Just gotta swap out the characters. And honestly, using it in a good work of fiction would help its popularity immensely. Just look at the number of people who study Klingon or Elvish.