There are some realistic ways that fluid fuels could be produced for this mod without needing to add world generation for oil and such, using only vanilla resources.

Coke oven: This is a thing in several tech mods already. Creosote could be used for the fluid fuel firebox, but would not realistically work in anything else. The coke/charcoal could also be used in a better steel recipe.

Industrial Pyrolyzer: A more advanced version of the coke oven which not only produces creosote but also collects the gases released. The "syngas", consisting mostly of hydrogen and carbon monoxide, can be used to power internal combustion engines.

https://splainex.com/waste-pyrolysis.html

Steam Reformer: Uses steam to completely break down solid fuels, producing even more syngas and leftover solid mineral waste such as sulfur. However, no significant creosote or coke/charcoal is yielded from this process.

https://www.clarke-energy.com/synthesis-gas-syngas/

Catalytic Reactor:

Converts syngas to heavier fuels such as diesel.

https://www.sierraenergy.com/technology/knowledge-base/end-products/diesel-other-fischer-tropsch-liquids/

Creosote could have immediate applications in the mod for the fluid fuel firebox and crafting recipes, while syngas could be used for more efficient gas turbines or gasoline engines in the future. Diesel could be used to power a diesel locomotive or diesel generator. Additionally, all of these machines would be able to be built with no additional resource types.

Thank you very much, for sure I will add some of these processes if not all