The phone delivers important news which must be checked at least once a day, and also is a core mechanism of socializing. I think you can't just randomly ignore it for arbitrary amounts of time.
What you can do is cut back on your digital socializing. Which means interacting with fewer people or less often. For me that comes naturally, but on days where I have even two people chatting with me routinely, it easily starts to eat into my attention for work and other things.
The trick is to avoid Facebook entirely, not have friends, and not have any followers on Twitter that are not bots.
> The phone delivers important news which must be checked at least once a day
I'm beginning to think the news is really not that important. Even in the midst of a global pandemic when presumably the news would be crucial to explain how to keep you and your family safe it's not clear it helped given the noise level of the information published. At the crucial early stages, being informed (masks don't help! don't buy them: https://www.marketwatch.com/story/the-cdc-says-americans-don...) would have hurt you (whoops our bad: https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-si...). Being largely uninformed and just getting the gist of information might have been fine.
When I go on vacation and stop checking the news for a week, i'm amazed at the volume of information I missed, how much I enjoyed not thinking about said information, and how unimportant it truly was in the grand scheme of my life.
I think many (most?) "Digital natives" already found a superior answer to these problems; pull people you're actually friends with (defined by whether they'll join your small group chat) into small group chats, and blog the daily experience of life mostly into those small chats.
Solves many privacy problems (but not all), avoids Dunbar number violations, and gives a genuine source of social attention (which humans need) from people who are more involved in your life.
Getting enough social attention (and giving enough in turn) seems to calm a kind of anxiety that might otherwise suck people into social media.
> The phone delivers important news which must be checked at least once a day
I think you've nailed the reason why it's very difficult to completely cut your phone out of your life in terms of it being something you depend on in your routine. It's relatively easy to block social media and uninstall apps like Instagram but for me this was the use case that I hadn't been able to find a substitute for.
I build this service to deal with this specific problem, essentially allowing you to have news and other kinds of content (like blog posts) delivered to your Kindle to read in a newspaper format:
What you can do is cut back on your digital socializing. Which means interacting with fewer people or less often. For me that comes naturally, but on days where I have even two people chatting with me routinely, it easily starts to eat into my attention for work and other things.
The trick is to avoid Facebook entirely, not have friends, and not have any followers on Twitter that are not bots.