Here is a full list of the rules and what they can take. Some things are standard for everyone and then there is a long list of optional gear but you are limited to ten items of the optional gear.
https://www.history.com/shows/alone/articles/gear-list
The most interesting part of the show to me is how the mental aspect of the game is harder than the physical for a lot of participants.
After about a month there is a standard health check once a week. A medic will be dropped in to take vitals and what-not. Also, someone is watching the cameras. If a contestant is seriously hurt and can't call for help, someone will come check on them but it could take as long as a day before help can arrive.