@pvp Hey, looks like you’re going down the same rabbit hole I got stuck in for a good while. Let me go ahead and summarize everything I’ve learned to save you some time.
For LaTeX and their alphanumeric style, be aware bibtex/biblatex, unless otherwise told, actually use their own custom engine (someone who knows more should correct me if I am wrong) to format citations. Meanwhile, Typst uses the standardized .csl file format (really XML) to format both citations and bibliography. Thus, for the alphanumeric style, the issue is that it’s associated CSL file doesn’t have settings for alphabetic sorting in the bibliography. See:
for that mess. in particular, you can use the .csl file at:
which has alphanumeric sorting for the bibliography. However, it, or maybe the Hayagriva engine Typst uses, has an issue where year disambiguation doesn’t work; that is, if you cite two papers by the same person in the same year, they will come out as the same citation, like two separate instances of [Doe99]. See