Ive always wondered where the inflection point lies between on the one hand trying to train the model on all kinds of data such as Wikipedia/encyclopedia, versus in the system prompt pointing to your local versions of those data sources, perhaps even through a search like api/tool.

Is there already some research or experimentation done into this area?

The training gives you a very lossy version of the original data (the smaller the model, the lossier it is; very small models will ultimately output gibberish and word salad that only loosely makes some sort of sense) but it's the right format for generalization. So you actually want both, they're highly complementary.