I used to do a lot of cross country driving. Here are my recommendations:

AAA membership if you don’t feel comfortable changing your own tires, a good lug nut wrench and bottle jack if you can do it. There’s a lot of areas where you’re “in the middle of nowhere” and it can take some time for any support to get to you. Make sure your spare has air. Audiobooks, podcasts, and playlists downloaded. There may be long stretches of no service. If you can download the Google Map or Apple Map for your trip, it’s not a bad idea. Non-messy snacks, gum, and a small cooler of drinks if you want to save money. Gas station food/ drinks add up. There are a few apps to check rest areas/ bathroom recommendations. I liked Trucker’s Path but it’s been a while since I’ve travelled like that so there may be others/ better ones. Get a dash cam before you go. There’s a lot of idiots out there. And the more you’re on the road, the more likely something could happen. Plan a little time to make some extra stops if you can. There’s a lot of neat stuff you can do on your way that you won’t know about until you see signs for them. Or check Google Maps for places to stop on your route. Get out and stretch your legs somewhere fun. And when you start to get hungry, look for good local spots to stop and eat. There are TONS of options that are so much better than the chain restaurants. Look for 4-5 star places in the area on Google Maps.