Ketogenic diets used in epilepsy go far beyond a bit of heavy whipping cream in your morning coffee.

A classic ketogenic diet would require significant quantities of heavy whipping cream (or MCT oil or other oils) with every meal, including snacks. Wikipedia has a good example: https://en.wikipedia.org/wiki/Ketogenic_diet#Classic

Doing a true ketogenic diet is hard work. Most of what people call ketogenic diets are actually more like Atkins or low-carb. Going into full ketosis requires significant protein restriction and augmenting with significant fat sources.

What do you consider “full ketosis?” Is that defined somewhere?

There are test strips available to indicate your ketone levels. You're in ketosis once your blood ketone levels are at or above 0.5 mmol/L.