I only have experience with YNAB, but can vouch for it. I’ve been using it for about 4 years now and while I’m not great at following a budget, it’s helped me make sure I’m planning for things that need to be planned for while also helping me figure out how to pay for a month of not wanting to cook 🤦♂️
It might be worth giving Helldivers 2 a try, it may not end up being his thing but it has a good few milsim elements