I mostly use the notepad app on my phone. Notebooks take me years to get through. I have some Moleskine type ones too but never use them because I feel like I have to write something profound and archival in them.

I used to use this thing called a Pocketmod ... no idea what I used them for though, probably nothing important. Prints on a sheet of paper, then you do a cut and some folding to make a booklet. There would be modules for general notes, scheduling, puzzles, etc. Original website unfortunately has since put it behind a login.
https://pocketmod.com/

Here's a template if you want to build your own.
https://www.agileleanhouse.com/lib/lib/_TrainingArtifacts/PrintOuts/pocketmod.pdf

And a web tool that looks like will take a pdf and do the page flips and arrangement for you.
https://pbtpocket.com/