List here: https://kadavy.net/distraction-free-writing-devices/
To me, YAGNI.
Let me suggest two cheaper alternatives (battletested by me):
1. Fountain pen and a nice notebook with nice paper (Mnemosyne, or Rhodia)
2. A foldable Bluetooth butterfly keyboard ($43 on Amazon) paired to an old tablet (I have an old iPad Air 2) with Wifi turned off and no apps except a writing app. Google Docs works in offline mode! (this is what I use in cafes when I’m traveling). I recommend a Samsers keyboard. This is what I have:
I love good typography and I just can’t with these distraction free devices. The iPad Air 2 has a retina screen that displays beautiful typography.
Forget e-ink devices — they might sound like a good idea at first, but their refresh rate is slow enough to be annoying.
If you don’t need portability, an old DOS PC running Wordstar or WordPerfect is also distraction free. I used to write long articles for my school newsletter using nothing but Wordstar.