Outdoor IRL is a niche from the IRL category. IRL is In Real Life, which is generally anything away from the computer or gaming console. Outdoor IRL is not literally only outside content. It is anything outside the home, not including your backyard with exceptions to bigger outside property and doing some kind of activity outdoors. Content that resembles a home may include hotel rooms, or other private spaces too that could give the same safety of “home” is not Outdoor IRL.
The purpose of Outdoor IRL niche is to showcase the live streamer exploring the outside world which should encourage viewers to do so as well. This is typically for viewers who live with a serious level of anxiety where they cannot or have a difficult time leaving their homes, or viewers looking to explore thru your eyes as the streamer and learn about these new places, foods, and experiences. This can have a double edge sword effect where it can enable someone to stay indoors more and encourage them to explore the world.