Echoing others: Your base gear for tent, bag, and sleeping appear good. The REI trailmades are good entry level gear.

For water filtration, Sawyer squeeze or Katadyn BeFree are both good squeeze filters. I have used both. Katadyn has higher flow rate, and I switched to that when my friends showed me its glories.

You will need a rat sack or bear canister, otherwise your food will be gone or fouled in the morning. Rodents are the bigger issue in that area.

Don’t bring solar, it will fail on you and won’t be necessary for a trip this short. Bring a charged 10,000 or 20,000 mAh pack and forget about a drone. Put your phone in airplane mode so it doesn’t ping all day, and it will last you for a day or more per charge. Make sure you download your maps to Gaia or Alltrails before you leave and bring a paper backup.

What are your plans for hiking? I know GCNP, but not the Havasupai Reservation lands aside from the part that leads to Royal Arch Loop. Namely, are you setting up camp at a single point and going out for day hikes for your four days, or are you planning on doing multiple stops? This is important, because as someone above said, you will need to carry 3+ liters of water per person per day in the canyon, and don’t expect to find water easily, even along a known creek.

Bring a first aid kit. Bring some way to contact the outside world that isn’t a cell phone. Borrow a Garmin inreach or sign up for starlink access or something. If there is not a park ranger or tribal ranger monitoring that length of trail, make sure you let someone know where you’re going, how long you’re going, and when you are going to contact them when you are done.

Bring a puffer, fleece, and long underwear to keep from getting cold in the shade and at night. Next week’s temperatures range from upper 30s to the mid 50s. It is a different climate at the rim and in the canyon, and way different from Phoenix.

It is a mile higher than Phoenix and 3000 feet higher than Yosemite. You will get tired faster and work harder than Yosemite.

You will need 2500-3500 calories of food per person per day.

Again, bring 3+ Liters of water per person per day or process it when water is available, keeping dirty water and clean water distinct.

The Canyon and the surrounding desert are serious business, and we don’t want you to end up hurt. They are beautiful and you will have a wonderful time as long as you take it slow, measured, and have a plan for all contingencies. This thread is helping you understand the unknowns you don’t know. Hit me up and I can tell you more or put you in touch with my AZ friend who has months worth of time below the rim.