Yeah so the smartphones and socials can be difficult addictions to shake, but this is the flip side of it: when you do put them aside for an extended period of time you often see your productivity absolutely go through the roof.
I started sticking my phone in my bag or in another room during my afternoon work session and my productivity with that time doubled, in terms of actual output - tasks completed, lines of code written etc. and probably better ideas generated.
I started turning it off after dinner as well as running a simple script that blocks FB, Reddit etc. on my desktop - my "productivity" with my evening time also basically doubled, whether it was books read, games played, extra work done, time spent with people who matter, keeping my place cleaner, etc. just more life happening basically.
The more hooked you are, the more massive the benefit of quitting cold turkey. Once you see it a couple times the dynamic inverts and it gets harder to go back.
From personal experience, yeah of course if you rip the phones out of the kids' hands they're going to experience a variety of improvements... that's what happened when I ripped it out of my own hands.
I do find it interesting that this study saw little in cognitive improvements - it was only a 21 day study. I thin they are there but they're a long burn, reading books for instance is a skill that has returned to me but it's been very slow and gradual, I should probably lean even harder into turning off my phone and any short-form socials trash.