Is there a tiny e-ink note taking device with a stylus which you can fit in your jeans pockets? It would be very handy to have something like that with you, even better if it could fit in wallet.
Search for "e-ink smartphone" and you'll turn up review pages such as:
<https://www.e-ink-info.com/e-ink-devices/mobile-phones>
Among the smallest devices I've seen is the DoCoMo Card Keitai KY-01L, though I don't know if it offers notetaking. It has a 2.8" display (diagonal measure).
<https://www.docomo.ne.jp/english/product/feature_phone/ky01l...>
Note that the software matters, as depending on the level of interpretation going on there may be considerable pen lag.
If the pocketable requirement isn't a hard one (or you have large pockets), an e-ink reader starting at about 6--7" is far more usable. You'd be looking at devices similar to the Onyx BOOX Poke 3:
<https://onyxboox.com/boox_poke3>
I have a larger Onyx device and can vouch for its notetaking app (something I'd not expected to use at all but find quite hand). There is no noticeable lag when writing. I've seen some in complex graphics (many strokes / elements, usually created by repeatedly copying a fundamental image block).
Most digital notepads seem to be 10" or 13" devices:
<https://goodereader.com/blog/reviews/top-10-e-ink-digital-no...>
<https://www.e-ink-info.com/e-ink-devices/e-notebooks>
There's a similar question from Reddit:
<https://old.reddit.com/r/eink/comments/f98zvr/eink_a6_paper_...>
I would not suggest putting an e-ink device in a wallet. You will crack the display or mainboard. A reporter's paper notepad might be what you're looking for instead.