15 years ago while resisting the smartphone shift I got myself a passport case to use as a combined wallet and portable notebook to write things down in. It worked reasonably well and certainly had some robust advantages but honestly so do cross-device syncd apps that I've used since smartphone adoption.
I hate those cases, but yes, synced todos (including grocery lists!) have been the killer app for smartphone use for me. Still, once I got my S20 this year I stopped doing it as much because the thing is too damn huge to be worth it. I've gone back to using a moleskine and it's fine, but just one more thing to carry around.
