Good points. However unlocking the phone in the morning puts my son on the wrong track: you would be surprised how much time one can spend checking animated gifs by using any text field that will inevitably be unlocked as well.
Of course I will take full responsibility in case of bugs... So far it didn't happen.
I applaud your efforts to keep your son from being addicted to screens.
While I'd be more conservative in the setup (I'd probably go with a device without inputs that turns on just to browse to a website directly, making any browsing mistakes or changed layouts less impactful), I do wish there were better alternatives for parents than "hand your kid a smartphone".
In an ideal world, schools would use some kind of one-way messaging devices to get the benefits of modern technology without the addiction smartphones bring, but I don't think we'll see that any time soon. Perhaps something like a (locked-down) Remarkable e-Ink tablet with a cellular network connection to receive school notifications and schedule updates as well as for doing homework in could prove quite useful, but that also sounds way too expensive for schools at the moment and you'd need to lock it down so that it's no more distracting than a piece of paper.
Of course I will take full responsibility in case of bugs... So far it didn't happen.