As someone who's used one before. I can see the benefit. But in order to be useful, it would need to replace something. Right now, the main thing it replaces is tablets. Me personally, I dont care for tablets and its also why i dont like folding phones. Either I do whatever I need to do on my phone or my laptop.
But the more interesting idea is it replacing the laptop. The idea of a singular device being able to run both desktop and mobile apps, makes it a little more intriguing. The closest you can get to this right now is Samsung dex (and I think android 17?). Hopefully in the future though, Linux phones will become more stable and useable. That'd genuinely be amazing.