What to take as snacks and drinks:
In higher altitudes carbohydrates reduce the risk of altitude sickness. Carbohydrates and protein also nourish the strained muscles. So you could take a piece of bread and dried meat. Some cheese for fat intake is also good, but don't pack too much "heavy" stuff overall, otherwise, you will feel sluggish after eating. Cereal bars, nuts, dried fruits (and a sugar-free chewing gum to neutralize, otherwise tooth decay will soon be imminent) are always with me.
As a drink, I mix water (still), syrup (or fruit juice), and a pinch or two of salt. AND: I don't skimp on weight by only taking 1L of water. It is not good for your body, which has to do a lot, nor for muscle soreness, which you can reduce significantly or even avoid. So drink a lot! Yes, that is the bad news - fluid spoils your meticulously packed backpack. I make sure to always have pure water with me in addition to the mixed drink - good for rinsing your mouth so that the sugar doesn't attack your teeth all day, or in an emergency, it can also be used to rinse wounds if you don't have disinfectant at hand. And when you need to go, also more often, that's okay! Please do not leave tissues behind - they decompose extremely poorly. Either don't use them in the first place or pack them in a plastic bag and take them back down with you for disposal.
In general, especially in the mountains: We take back any waste we produce!
Regarding the use of drinking systems, everyone should decide for themselves. Rather, think about insulating your drinks, whether in a bag or a bottle, when climbing to higher altitudes or touring in winter (thermos or insulated bottles, there are also very lightweight versions). Cold drinks when you are in a cold environment promote internal cooling.
In the morning, I'm not such a big eater, but I make sure not to start with an empty stomach. Rice pudding (which I usually buy) serves me well, in which I mix dates, walnuts, and one or two dried apricots, and if possible, a few berries. With this mix of protein, carbohydrates, fats, and minerals (especially calcium and magnesium), I don't feel weighed down but still have energy. But everyone has their preferences. I would advise against a very heavy breakfast - of course, it can also be an egg, maybe just not three fried eggs with bacon - it tastes great, no doubt, but it doesn't really activate you ;-)...
But yes, as you see on the picture, it's also (all) about enjoying the mountian lodges.