I'm interested in 3d printed reaction chambers, but can't find any good information on chemical resistances of PLA, just vague claims that it "might not be" "because it's biodegradable" or that it depends on additives (likely true, but it would be nice to know if there's hope of finding PLA without problematic additives if the PLA itself is okay). Is there any published research or even anecdotes (which could suggest it's worth spending effort to investigate further) on this topic?
As @T. M. notes in his comment, there are many good charts of chemical compatibility with various agents. Very few (I found none) include information about PLA. By all means, use search engines to find some information.
But, no data source is as true to your specific needs as is testing your candidate materials with your agents.
As a first test put the agent in a tall thin jar or test tube. Use a few test filaments so that the ends are dipping into the agent. Check for signs of dissolution, swelling, softening, or any relevant change in the material's characteristics. Examine the candidate filaments right away, then after minutes, then hours, and if any material survives, perhaps in days.
Print test objects. Test them with your agent. Try until you find something that works.
The online material compatibility tables will help you eliminate materials before testing them. If it says a material is incompatible, it probably is incompatible. If rated as highly compatible, it should be tested because the formulation of a filament may not match the material tested for the compatibility tables. If you are running out of options, try the intermediate compatibility plastics.
Bottom line, use the online information to help direct your search, but you should do your own tests.
The paper Chemical Compatibility of Fused Filament Fabrication-based 3-D Printed Components with Solutions Commonly Used in Semiconductor Wet Processing, found by user R Kiselev in the comments on another question, has results for this, and finds (this is summarized; details in paper) that PLA has fairly good resistance to HCl at 37%. It did not fare as well against other acids or solvents except IPA.