As far as radios, I recommend the Baofeng/Mirkit UV-82 (not hp version). A lot of folks recommend the Baofeng UV-5R which is a great radio. The UV-82 has the advantage of having independent buttons for the push to talk where one channel is channel A, and the other is B. The difference there is that with the UV-5R, you can LISTEN to both at the same time (you can with the UV-82 as well) but you have to do a dance on the buttons in order to be able to transmit on one channel or the other. If you're not running with a team and need to be able to easily get ahold of both your squad and command at the same time you can go with the UV-5R, or if you need a radio to be able to hand to command and say "this is how you can get ahold of me", you can use the 5R for that. I prefer the 82 because my role on the field is usually as a communicator and forward set of eyes for the commander so I need to be able to easily communicate with multiple parties.

Here's a good package deal for the UV-82 including an extended battery, regular in ear headset, dual ptt shoulder mic, and everything you need to be able to program the radio. https://www.amazon.com/Baofeng-Tri-Power-Upgraded-400-520MHz-Programming/dp/B074KFGZS6/ref=sr_1_18?dchild=1&keywords=baofeng+UV-82&qid=1612056298&sr=8-18

Just so you know, these can also be used for HAM radio and weather radio purposes as well if you program them correctly and have the right licenses. If you keep the radio on normal FRS/GMRS (the software to program the radios will tell you what these are) frequencies you shouldn't have to worry about crossing into the wrong areas. (I advise you to do your research on what the frequencies are as well too. Getting licensed is a good idea as well)

Hydration pouches - I swear by 3vgears hydration reservoirs. They're top fill, which makes them easy to fill, drain and clean when you need to. You can get a 2 liter reservoir, or they have a 3 liter one but those are sold out right now.

https://3vgear.com/collections/hydration-systems/products/hydro-tanker-2l-top-fill-water-reservoir That's the link for the 2 liter reservoir.