My wife and I divorced last year. Fortunately, she and I have always agreed on this parenting philosophy for our kids. Unfortunately, that means I can't totally relate to the specific tension you're having, other than to guess that it must be very hard that the two of you disagree on something so intermingled with today's parent-child relationship.

A screen is a great way to amuse a kid while you regain your sanity after a rough day. But so is a playdate with another kid, or a sleepover if they're older. And if your kid went on a playdate or a sleepover, wouldn't you ask how it went? Wouldn't you talk to the other parent(s) about how it went? Wouldn't it be weird if you didn't ever talk about that sleepover? Why should an iPhone be any different?

My point is that a screen isn't a pause button on your parent-child relationship. It's an experience that the kid goes through, separately from you, and it's your duty as a parent to get back in sync again afterward. Sorry to use your kid's mom as a pointed subject here, but it makes all the difference whether she sees the iPhone as an extra parenting responsibility, or a substitute for some of hers. In our case, we didn't demand a full accounting of every one of our kids' clicks. But occasional conversations were expected. (And pro tip for separated parents, these kinds of conversations can also happen... over the phone! On SMS!)

Stories to share... well, I won't get too specific because they're kids and all that, but briefly...

One: the kids all have small savings accounts with even smaller allowances. Twice they've gotten bamboozled by online gaming sites (similar to Club Penguin) into putting in their debit-card number to buy a virtual trinket that then turns into a $expensive/month subscription. Both times they noticed they were suddenly overdrawn, and came to me asking for help. If those payments were tuition in life experience, we got good value for it, because my kids today are pretty good at reading the fine print. And we now have a family legend/parable of Kid #2 buying the $1 powerup that cost him all his savings.

Two: Call of Duty during the pandemic. Self-regulation issues surfaced, and grades slipped. We talked about it and came up with a homework-before-gaming-each-night rule. We (the parents) didn't enforce the rule; that was the kids' job. Grades came back slowly, but the bleeding stopped almost immediately.

Honestly, I sat here for a while trying to think of a zinger of a third story, but most are the same -- the kid walking up to me with a screen in hand, showing me a site or an app, and asking "Dad, is this legit?" and oh god no it isn't and I'm so glad they felt OK asking me about it. I think that's actually the common thread with all these stories: we've been reasonably successful keeping the lines of communication open about their online lives, giving us the opportunity to parent through the teachable moments, rather than preemptively shaming them into dealing with it alone. My kids aren't perfect, but I'm satisfied with how they're prepared for the world, in all its gory detail.

Best of luck with your parenting! If you do it right, your kids will grant you lifetime tenure!