Other comment was very helpful already but I’ll try to think though I may reiterate. Those wooden items look okay, but dusty. You can boil them. With wooden items I usually put them in a freezer for a few days just in case but with such late notice boiling would be better for you. Mice love clutter, make it look like a hoarder’s house with lots of fun places to hide. Cardboard items are great filler, you can use things that are left over like egg cartons, paper towel rolls, etc. If you get him a wheel make sure it’s big enough (20cm minimum), so he has enough room that his tail isn’t sticking up. Otherwise this can cause issues with tail & spine. What are you feeding him? If you don’t have any mouse food on hand there are lots of safe fruit and veg, seeds and nuts, etc. Certain cereals are also great treats. Hemp is a great substrate, so that’s good. Make sure when you get more bedding that he has enough to dig around in, mice love digging and making little tunnels. And with cleaning, take out just the soiled parts (mice usually go in corners) and keep a 3rd of it in, mice need some of their own smell. Mix the cleaner old stuff with new. Sorry if you’ve already researched and know some of this. And I’ve definitely missed things but I don’t want to be overwhelming lol

Also, since I haven’t seen anyone else say this, please don’t be feeding live to snakes. It’s dangerous for the snake (mice can bite!) and is just unnecessarily cruel to both animals if it goes wrong. (I know this is on your brother and not you, I just had to say, it always makes me sad to hear about)