Here's an idea.
Breakfast: Keto porridge made with unsweetened almond milk ( I buy Alpro Almond No Sugars Long Life - it is zero carbs
https://www.tesco.com/groceries/en-GB/products/276761995 ) - you can use it for anything you would use dairy milk for and it is excellent.
Keto porridge is made with a teaspoonful of coconut flour and another of almond flour/ground almonds - also easily obtainable from tesco and a spoonful of erythritol mixed together and zapped in the microwave for a minute or two until it thickens. You can then stir in a teaspoon of Greek yoghurt - plain with only around 4g of carbs per 100g so a teaspoon is hardly any carbs.
This is nutritionally dense and high in fats and proteins and other minerals and is very filling.
If you buy a bag of psyllium powder from Amazon you will then be set up to make extremely low carb cakes. What you start to change in your thinking is that a cake is now on keto an actually healthy meal choice.
You can make a mug cake with one egg and a tablesppon of melted butter, a teaspoon of almond flour/ground almonds another of coconut flour and one of psyllium powder (
https://www.amazon.co.uk/Organic-Psyllium-Foodies-Servings-Maintain/dp/B08BZR7YCH/) - half a teaspoon of baking powder and some erythritol to sweeten.
The psyllium is fibre and people actually take it in water as a health supplement!! The almond and coconut flour has fat and protein and the butter of course has D vitamins and healthy fats.
If you add some nutmeg and or cinnamon or a teaspoon of 100% cocoa powder - it becomes a chocolate cup cake.
you mix the powders together and beat the egg with the melted butter and then fold the dry ingredients into the wet ones and then zap in the microwave - you will have a decent size individual portion cake.
You make jam from three strawberries and some erythritol zapped in the microwave and then stir in some chia seeds and wait a few minutes - the chia seeds will thicken the jam. Chai seeds are also available from tesco. A spoonful of jam and a tablespoon of whipped double cream (or if you want to save time - extra think double cream from tesco) can be sandwiched in the cake and you have a very quick and very yummy and extremely healthy meal that is not going to cause you any trouble with your diabetes.
I don't know where you get the idea that keto is about meat.
If you are not gluten intolerant then keto yeast bread is nearly entirely protein as the major ingredient is vital wheat gluten which is almost 100% protein. The rolls I showed are basically balls of protein. You can have them with anything you like. Even just spread with butter and some marmite and they are fine as a meal. Keto bread is not like ordinary wheat bread which is just empty calories and you have to have something else with it - keto bread is packed with fibre, huge amounts of protein, vitamins and minerals - if you chose my favourite keto bread recipe it includes ground wheat fibre and that holds all the vitamin Bs and another recipe uses flax seeds and they are incredibly nutritionally beneficial especially for PCOS.
The diet recommended for curing PCOS is a keto diet with plenty of flax and other fibres and only a moderate amount of meat. Vegans and vegetarians have been making something called Seitan forever and that is a protein meat substitute made of vital wheat gluten - so that gives you an idea of how protein packed keto yeast bread recipes usually are.
You could eat lettuce sandwiches and that would be a perfectly fine meal if you make them with keto recipe bread.I realize its not about meat but thats the only normal ingredient. Flour is not freely available. Milk is not what he would have so more expense and even more strange additives he'll not go for any of it. Hes thin and not diabetic so his idea is cut out all luxuries and eat normally so I cannot do your fad diet.I have tried looking on the web sites and yes somethings even in those I would not have or eat or like. Flax seeds have very high cal content so I use them sparingly and some say even then its not the right kind. Keto bread is £5 a loaf delivered so even if I froze it he'd say he have 12 loaves for my one so its a treat he is not going to be persuaded into. I am not gluten free and hed say the Gp would supply that if needed.