I put my phone in "do not disturb" mode for the entire day. Removing notifications altogether was a great improvement, without getting rid of the phone altogether. You go from responding to picking it up when you decide to.
i've started to just chuck it somewhere if I'm trying to focus
When I got a new phone about 6 months ago, I spent about a week horrified by the number of notifications that I was getting by default.
That, and keeping the charger in a remote corner, helps to park it and forget it.
Also, disable face/fingerprint/pin unlock, and use a longish password, so unlocking it isn't convenient.