I plan exclusively on paper despite using Obsidian quite extensively for taking notes. I also do weekly and daily planning.
Initially I tried to plan on Obsidian as well but it didn't work for me. Writing on paper is slow and not only it calms me down but also directly incentivizes me to state my tasks and goals concisely. Similarly, the limited space on a planning page helps me to be realistic in terms of things I set to accomplish.
You can go through a text to be published 5 times on a computer, print it out and for any text of decent length, I guarantee you will find a ton of stuff you missed. I have never tried using an e-ink device for that to see if it has the same effect, but I would be curious of the feedback on that if anybody here has done so.
Initially I tried to plan on Obsidian as well but it didn't work for me. Writing on paper is slow and not only it calms me down but also directly incentivizes me to state my tasks and goals concisely. Similarly, the limited space on a planning page helps me to be realistic in terms of things I set to accomplish.