If you can't have surgery, there are two traditional, "cytotoxic," systemic chemotherapies. One is "gemcitabine" or "gemcitabine plus other stuff." The second is (modified) Folfirinox and variants.

Other options not typically used as first-line treatments or outside of clinical trials are certain immunotherapy drugs and targeted therapy drugs.

Radiation is common, but other techniques like HIPEC, Tumor Treatment Fields, or IRE (Irreversible Electroporation) are a bit more "out of the box" and hard to find a provider for.

Two good articles on the standard "Standards of Care" are here:
https://pancan.org/news/going-beyond-standard-care/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6176548/