I have not used a lot of pocket notebooks after covid, but I have gotten back into it recently. Especially when I have my daughter.
Since Field Notes still haven’t gotten their act together and made a dot grid option generally available, I did the switch to Travelers Notebook a while back. And their passport size is awesome for pocket notebooks.
Most of the time I use it with gel pens, most of the time a Signo or Hi Tec C. But it also handles fountain pens really well.
In general this setup is really great. The covers are awesome, it handles all my pens way better than Field Notes and I can get all the formats I want. Plus using pocket notebooks again have been good for my ADHD.