4k vs Open Gate on iPhone 15 Pro

So I'm trying to fine tune my settings on the BMC app on my iphone 15 pro. I think I have most of them down but I notice if I switch to open gate I'm only getting 1920x1440 resolution. Aside from having a wider field of view, is there any benefit of using Open Gate instead of 4k at that point? Also what is the overall benefit or use case of open gate in this scenario? I've heard a lot of people mention shooting once and being able to edit for landscape and portrait style content, would that mainly be the only reason?
I'm likely going to be punching in the footage when editing so I want to maintain the most quality and data as possible.