Food is trickier as that varies a lot and I don’t even do keto all the time, let’s talk about fasting first.
(I apparently can’t not going into details and you probably don’t need those but who knows, maybe you are interested how other people work and behave, I am.)
Gong low with my carbs damaged my fasting abilities (the opposite what most people experiences) so no EF for me (I hope I will be able to do it eventually, I want enhanced autophagy and other things!) but I still do IF most of the time. The eating window is individual, I rarely eat before 3pm especially on workdays and it’s true for my days with a huge eating window too, actually.
I eat 1-5 times a day, my frist meal is usually at 3pm (usually later on OMAD) and the last varies, my number of meals have little to do with it as smaller meals make me hungry in 1 hour. I believe 1-2 meals is best for me as I like and need bigger meals and they last wonderfully long especially if I choose my food well. I enjoy not being hungry, rather perfectly satiated and the less meals I have, the easier I get this. If I can eat enough to begin with but it’s not a problem if I choose my food well, again.
My meals are always close to each other (except on OMAD), nothing can change that. So it’s fine if you don’t last very long after a meal, some of us are like that.
I personally really try to finish my day around 6pm for reasons. Like I become a gremlin if I am fed after that time, satiation and satisfaction and good dietary decisions face problems there. So it’s quite personal. ~6pm is good for dinner as enough time passed since lunch (I may or may not be hungry yet but I surely can eat a decent sized meal again) and it’s not far enough from my bedtime for me to get hungry again as long as I ate properly during the day.
I can write a typical (albeit simplified) good day of mine:
400-600g not very fatty pork (but ruminants are great too, I just have multiple reasons to eat mostly pork. I do eat fish and fowl but they aren’t very satiating so it’s just some addition, red meat is needed), a few to several eggs and dairy in moderation. I can handle other things (plants) in little amounts without a noticeable change but it’s better to stay as close to carnivore as I comfortably can.
My off days are sometimes keto, sometimes not (the latter is rarely a good idea for me nowadays, my body likes my non-animal net carbs being super low), my keto ones are very similar to my carnivore-ish ones but with a little extra fruit or grain or walnut pancakes (the dough is carnivore)… I enjoy myself and non-carni food pretty much loses its charm for several days again. But it may be a slippery slope, it depends on the season a lot…
My old keto days were half sweet desserts and no meat, pretty far from my current diet. Still high animal protein, I ate 7 eggs a day on average for more than 10 years (I continued to do it on carnivore too) and I really love dairy. I am fine with dairy, the sugar is okay too (40g sugar on a carni day? feels like I had 2g! so different from plant carbs!) except it easily triggers overeating in me. Many of us are like that. I don’t overeat cheese or any other dairy item, actually but I consume various items and the fat easily adds up while I don’t get more satiated. Many of us need to be careful with dairy for various reasons. My main pillars are meat and eggs but I try to focus on (red) meat more as that is what satiates me best and what my body misses if I eat too little of it.
I eat organs as they are cheap and nice. I eat as much liver as I dare (it’s too nutritious). 500g per 2 weeks seems okay.
I used to avoid added fat but now that I base my diet on lean meat (green ham, the fattiest I can find. not super lean but pretty lean) and don’t eat a ton of fat from dairy, I can snack on butter IN MODERATION
(It is dairy but I consider it ‘fat’, another group for me.) Scratchings too 
I need my super tasty fatty items for my mental health 
My food choices may not be typical but it’s because I need and love protein so I need a lot while my energy need isn’t much (and I am in love with high-fat since I was born. or a bit later, I am not a seal, I surely didn’t get fatty food as a baby). Very nicely fatty food gives me way too much fat (as no way I stop eating below 130g protein. I am hungry there) hence I eat as lean as I can and I can do it WAY better than before carnivore, yay!
I don’t know if you want to eat sweeteners… It’s better for some than for others… I never noticed my sugar alcohols would be a problem (I hate the other options or never tried them) but I love sweets so they may trigger unnecessary eating. Not a very serious one, my sweets have too much protein and fat and satiation effect for that.
But some people avoid sweeteners and even sweet things for good reasons.
Even I don’t consider eating a lot of sweetener good in my case (others may do whatever suits them or want), it’s not food! So I trained myself to keep it low. It completely disappeared from my coffee, even from my cocoa, at some point from my chocolate… Then carnivore came and after a few years I noticed that I almost never even think about sweetening my food even on my off days… One can change a lot.
I eat plenty of sweet things though, even on carnivore as there is all that lactose
Our sweet perception tend to change a lot when quitting added sugar, it happened to my family members (even if they kept eating a lot of natural sugar and sweeteners), it quickly happened to me on low-carb then it stayed there for several years, keto did nothing to it - but carnivore did. No wonder. Having sweet off days can’t stop this and I still feel things with sugar (like most dairy items) sweeter and sweeter.
But I don’t expect sweetness from my food nowadays so that helps too.
Oh and I find it important that sometimes being stricter is easier. When I tried out carnivore for the first few (or several) times, it was so much easier than keto! I couldn’t even do keto back then, if I added more than minimal plant carbs, they messed with me and I couldn’t stay on track. Carnivore is simpler too and that may feel quite nice. (Not like I don’t tend to overcomplicate it but it still not as complicated as my keto. And I am getting better anyway I think… Baking is especially simpler. Well. Less items to choose from
)
Good luck, I stop myself already…
Oh, nutrition wise I don’t know if I lack something. Cronometer says I do but my body doesn’t tell me to change something. I supplement nothing. I don’t think my off days help much with nutrition but I hope I can see what happens during/after a mostly carni winter.