First, this app doesn't actually use the glycemic index (GI) of foods because the GI has an excessively high false negative rate (type 2 error), meaning that a 'normal' blood glucose response will often be given in the context of a hyperinsulinemic response.
So we're definitely not "a GI list in an app that monetizes your data".
Second, how many grams of ketones you produce shortly after being ketotic vs long-term ketosis is not at all clear and still an empirically open question - the downward trend is still just a guess based on anecdotes (nothing wrong with that).
Third, your comment about IF and carb loading being necessary to keep ketosis going is simply incorrect. You can stay ketogenic without carb-loading, since this will acutely increase the oxaloacetate-to-aceteyl-CoA ratio, thus diverting fatty acids away from ketogenesis. I think your comment may be in reference to staying 'healthy' in ketosis? Like not tanking your thyroid hormones? Thyroid hormones don't tank because of ketones, they often tank because of chronic caloric restriction - a common scenario in a fat-loss scenario.
Lastly, you're right that many factors keep you in or out of ketosis. You seem to know more than the average person yet even you are not entirely up to date on the clinical side of it, and this is precisely why our app would be of great use to you and other less knowledgeable users: you'd have somewhere to share your metrics, meals and see how it all compares with others if you have a blood glucose readings for instance, or your fasting triglycerides and insulin values. All nicely organized and presented from within the comfort of 1 app.
I wouldn't write it off until you've tried it ;)
Beyond dropping carb intake there is a huge variation between people as far as insulin production and BGL goes which depends on their general life style, time of day, time of year and how they react to specific foods and even at which combinations.
This variation can only be calculated on an individual basis with BGL meters.
I don’t see this service being any more useful than a generic GI list because that’s just what it is a GI list in an app that monetizes your data.
As far as being on a ketogenic diet healthy young individuals can product 100-150g of ketones a day this figure goes down the longer you stay in ketosis.
If you want to keep ketosis going longer for the specific intention of reducing body fat then intermediate fasting and carb loading is required with a healthy dose of physical activity.
This again varies greatly between individuals some people might get knocked out of ketosis for a few days after carb loading some might be knocked out for weeks, how much ketones they can also produce and for how long to begin with varies a lot and more importantly how much carbs you can intake daily while staying in ketosis also varies same goes for if artificial sweeteners and non-metabolizing sugars like alcohol sugars would have an effect or you or not.