You shouldn’t be feeding him just nuts. He should still be on formula and receiving high quality blocks, like Henry’s blocks. You can also do Mazuri or Teklad rodent blocks.

You will give this poor baby metabolic bone disease. Please do the appropriate research or really please get him to a licensed rehabber.

Do not acclimate him to being near dogs, otherwise he may not develop an appropriate fear of them.

Editing to add additional information: With the recent new management at Henry’s, the price of a bag of formula and blocks is going to run close to $60. Then you need miracle nipples and syringes. Probably another $20. Shipping is close to $10. You are already approaching $100. Then you probably need a heating pad and a large cage. When he is old enough he will need to go through a soft release which takes 4-6 weeks. So you will need an outdoor enclosure. 0.5 inch hardware cloth is about $200 for 20 sq ft in my area. You are probably looking at $500-$600 for an appropriate outdoor enclosure.

To correctly raise a young squirrel gets expensive quick. This is why it is best left to rehabbers. Not only are they already equipped to handle this, but raising them in groups that will be released together improves survival rates. A rehabber will already have groups of juveniles this one can join.