Interesting idea to use Apple Configurator, I like it! I use a combination of uninstalling any interesting apps + Foqos + One Sec + grayscale.

This works pretty well for me, and the key part is Foqos, which is FOSS that allows you to disable certain apps or features with the scan of a QR code or NFC tag. I keep the QR code / NFC tag in a separate building or locked box, so there's real friction if I want to scan it to use the phone beyond basic functionality.

Like the OP, I also have the issue of "semi-important" things, which is mostly email but occasionally some browser thing (often buying or viewing event tickets.) My plan for that is to use Foqos in combination with a QR code + scratch-off sticker, a sort of "break glass in emergency" option that adds some friction but not too much. Print a sheet of identical QR codes, scan it into Foqos as your unlock option, put stickers over them, cut them out and put them in your phone case.

Wow I'm the creator of Foqos, thanks for the shoutout <3

greyscale is a game changer. i wasn’t a believer until i forced myself to use it, but it really turns off the appeal. have you ever seen someone just staring at their phone and flipping through the home screen(s)?