I switched to a candy-bar style dumb phone for a month and did something similar. My list was pretty much the same as the one in the article with a few small changes.

The most jarring was probably maps - other things like email, messaging etc could be delayed until I could reach a computer but not knowing how to get somewhere right now was problematic and required planning in advance.

I usually kept my smart phone in my car and did a sim swap on the occasion that I really needed it.

same experience. switches to an old school dumb phone. my neighbor joked that I was a drug dealer, lol.

but man did I miss maps. need to go somewhere? get in the car, start the engine, look it up on some map app, and then I'm off.

text messaging and being able to send simple photos was also a loss. definitely missed being able to text the wife a photo of something on sale in the grocery store ("hey, 10% off X, wanna give that a try for dinner?"), and I missed how good some of the auto-fill was after a while.

to a much lesser degree, a phone was nice during some downtime. waiting in line for something, killing time in a doctor's office waiting room, etc. 20 years ago they had magazines, now they don't...

eventually after getting lost a couple of times I just tapped out and went back to the Pixel 4

Out of curiosity, how often do you need to travel to somewhere that you don't know how to get to and haven't been to before?