Hi! This is one area I’m really interested in, so I know a lot about baking for people with allergies.
Basically what you’ll want to look at are two things: flourless cakes, and cheesecakes. Flourless cake (or at least the keto varieties I know of) are made with egg and dairy, plus things like cocoa, sweetener, flavourings, and then additions like xanthan gum to create the right kind of squashyness. Other ingredients are things like ground chia seeds and ground flaxmeal to add fibre. You might get some recipes for cookies that use chia seeds as a base with egg for extra binding and butter to cook, I think it’d taste a bit like oatmeal cookies.
Cheesecakes are another great option because you can make the base from butter and flaxseed/chia seeds, plus cinnamon or sweetener to taste, and then the cake itself is just lots and lots of cream cheese with, again, sweetener and flavourings. The baked cheesecake I do uses egg as well but there are a lot of no-bake recipes out there that use heavy whipping cream. If you can’t get a base that you like, you can also just make the cheesecake without and then go a little easier on the flavour.
Apart from that - fat bombs! There are SO MANY RECIPES for fat bombs. Many will use things like peanut butter as a binding, just ignore those and look for ones that use butter or egg to bind instead. Some use cream cheese similar to how it’s used in the cheesecakes.
There isn’t really any good flour alternative that isn’t nut-based, apart from what I’ve mentioned above, in my experience. If you really want to get into baking keto-friendly desserts and treats, then you will have to just toss out all your recipes that use wheat flour. Keto baking is a whole other game with different rules.
If you’re also allergic to egg or dairy (or you’re a vegan), then all I can say is: give up now before you drive yourself insane.
Sidenote: you can get things like wheat gluten and oat fibre, but I can’t really comment because I’ve never used them. I don’t see them much in recipes online apart from in those for bread, and I buy low carb bread instead of making it.
[edit] I almost forgot! Hemp hearts! I’m eating a hemp heart chocolate chip cookie right now
My particular recipe uses almond butter as well for flavour but I’m sure you could remove it and add some cinnamon or allspice or whatever you like.