Do people need foldables? Absolutely not, but I love mine. I went with the OnePlus Open mainly for the cameras, and the bigger screen is great for reviewing or sharing the photos with someone. Having two apps side by side is really nice but I don't really use that feature that often.
I think the bigger thing is having a screen that faces away from the main viewing side. Showing a live camera view or translating speech into text from another language are two good, but rare, use cases. I think what it really comes down to is how much do you use your phone and for what purpose?
^ This post right here. I also have Reolink cameras, solar powered wifi versions, and they have been great. The hub is perfect for storing the data as it has two SD card slots. Easily integrates into home assistant and the Reolink UI works well in the phone or computer apps.