You attach your phone to the controller and the sound comes through your bluetooth headphones that you no doubt already own. It's basically like using a Switch or a Steamdeck. With fast 4G or 5G network performance is perfectly fine for game streaming. Given that Nintendo have sold roughly 400 million portable consoles so far, it seems many people don't particularly mind "squinting" at a small screen when playing games.

As compared to just using a low end laptop?

Modern phones have better screens and faster CPUs/GPUs than many low end laptops.