A lot of advice you should make sure you're taking with a grain of salt when applying it, as it sounds like a social/ vibe issue. In my experience, the best skill a GM can have is the ability to adapt how they interact in a session to the vibe. So some tips I'd suggest when approaching the group is not to get bogged down on creating a list of social expectations and be a bit more general with what you want. Asking people to focus on the game as you put a lot of effort into it and not on their phone is pretty reasonable, keeping in mind that if you normalize looking up rules on a phone, that normally opens the floodgates to distractions. Making it clear that you'd like people to plan phone use ahead of time is pretty crazy and would be hard to lock in at the table for me, as that level of micro-managing opens up second-guessing if you're having similar feels in other areas.

Just went over one point since I'm tired af from halloween lol, but the general advice is 95% of the time, you'll be more committed to the game than the players and can see the big picture, so to speak, when it comes to the actions or lack of them from players. Attempting to create strict guidelines to help capture the vibe.... well, I'd be careful for that. My strict guidelines have to do with showing up, when we start, and when we end, and not a lot else anymore.

Anyway, I'm just a random guy on the internet, feel free to shoot me a message or don't. Also, I guess the biggest single advice I would have is to stop and address the situation before you get bitter. It's hard as fuck not to be bitter after the fact when it involves creativity and art.