We feed our cats and kittens Purina products. They are tried and true and recommended by vets everywhere. Not only that, but the cats and kittens LOVE it. They get one can of wet kitten food everyday and a bowl of dry food to snack on throughout the day. If you still feel a touch of allergy symptoms with your Siberian, try "Live Clear" dry food. The combination of a Siberian cat and Live Clear food should completely eliminate the Fel D1 protein. You should always use metal bowls as they do not grow bacteria like plastic or glass bowls.
One day there will be a cat litter that is neat, smells good and doesn't get stuck in your cats paws but until that day we do the best we can. My choice is Tractor Supply's Pine Pellets. You can get a 40lb bag for $7. It smells like pine and turns to dust as it gets used. It doesn't stick to the cats feet and dumps into a garbage bag easily. Clumping litter smells horrible and gets stuck everywhere even with litter robots. However, if you would like to go in that direction, the reviews show that the Litter Robot version 2 (not 3) is the best one out there.
We love TEMU. Between the toys, blankets, cat scratchers, etc. we get deliveries regularly. Deliveries are much slower than Amazon or anything in the states but if I am going to pay 4 times less for the same thing, I don't mind waiting. Groupon is my go to for cat trees. Siberians love to climb. They love to be up high. Groupons cat trees are great and the most affordable I've seen.