Took me awhile to get there, but my ideal mono-tasking "typewriter-like" setup is:
- iPad Air
- iA Writer iPad App[1] (or: Simplenote)
- TwelveSouth Compass Pro, for use in portrait mode[2]
- Standard Apple Bluetooth Keyboard + Apple Pencil clipped on side[3]
Also, I might be old-fashioned, but when I need to type outside -- which is often -- I just bring my laptop! Lenovo X1C (excellent keyboard) with a great matte screen[4]. Since that's Linux, I usually use vim + goyo, Typora, or Simplenote.
[1]: https://apps.apple.com/app/id775737172?platform=ipad
[2]: https://www.twelvesouth.com/cdn/shop/files/CompassPro-sectio...