G’day - I’m far from an expert, but perhaps my experience can help you. I agree it all seems a bit uncertain, but i think I got a grip on the key bits:
restrict carbs to 20g per day or less (this is the most important aspect);
try to eat enough calories to fuel your body, so the rest is made up of fat and protein. Ideally more fat than protein.
For me, I use Fatsecret to track what I eat. I was eating only around 900 cals per day prior to taking on keto. I entered my details on a keto website that told me I should be eating a lot more. I have since increased my calorie intake, but i still find it hard to eat more than about 1500 calories per day, so that’s what I do.
I have landed on a sort of diet that gives me lots of fat (eggs, bacon, avocado for breakfast, pork belly and green salads for lunch, with cheese; meat and salad for dinner if I need it (I sometimes skip dinner if I’ve had 1,500 calories by the end of lunch). Lots of water, a bit of black coffee. No snacks.). I enter each meal into Fatsecret and it tells me my carb count in grams.
I don’t count protein and fat beyond a quick glance. I look at the pie chart in Fatsecret to see if I can get 60-70% or more proportion of fat and that’s it.
From the first, I wasn’t hungry or craving for sugar or carbs. I’ve had my fat up to 82% of my day’s calories on one day (with 15.6g of carbs) and have steadily lost weight (I weigh myself weekly) and feel fantastic.
I found, to keep in the 20g range for carbs, I had to drop my morning flat white coffee and I only have fried mushrooms every now and then but its a process of monitoring my carb intake - the rest I pretty much leave alone, beyond trying to eat fatty foods.
I’d say aim to limit carbs to 20g per day or less and not worry too much about protein and fat - just make fat your friend.
Hope this helps.