https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7915550/
It's always good to remember just how crazy complicated and unusual HIV is, with its self-rewrite immune escape functionality.
The mRNA vaccine for covid-19 was very lucky, not only because coronaviruses are not the devilishly clever co-evolving with the host's immune system HIV type of things, but also because the spike protein was already "solved" ahead of the pandemic. By that i mean we knew how to create a version of the spike protein that doesn't require the full envelope to fold properly. The mRNA sequence was ready in January 2020, the rest was just manufacturing, testing and distribution.
The HIV vaccine will be most likely much more complicated, as the authors point out in the last chapter.
PS. Sometimes I wish I was a research doctor instead of a computer scientist, but I guess the grass is always greener :)