This is the first time I've heard someone say a smartphone reduces distractions.
As a millennial boomer, I prefer my triple monitor setup and mechanical keyboard, not to mention network- and client-level content blockers, whenever I have to input more than a sentence.
I was at a conference last week, and I took notes in a fullscreened GNU Nano. Distractions, ADHD, etc. Did get some odd looks, but I couldn't imagine taking notes without an actual keyboard. I'm not an ultra fast typer, but I'm decent - I'd challenge any thumb typer on MonkeyType.
I don't have any social apps or games on my phone. Other than the web browser there's nothing to distract me. I find it so easy to get caught up in checking the news or email or the episode of that show I was watching on my laptop, but I don't do any of those things habitually on my phone or tablet or reader so that's my "distraction free" device.
That's only for reading though! For taking notes I go with a real keyboard or pencil and paper whenever I have the choice.
similar here, I'm gradually removing more and more things from my phone. at this point it's mostly just a couple actually-important apps, a web browser, and messaging apps (because it's clearly superior to whipping out a laptop for brief things). "social" outside messaging is in the web browser or not on the phone at all. if I want to focus I just turn on Do Not Disturb for an hour.
browsing is slowly reducing as time goes on too, as while it's convenient on my phone, it's rarely efficient. it doesn't take long at all before I'd rather pull out a laptop and finish more quickly.