the act of writing it down probably makes them remember it.

This is absolutely the case with me. When I need to remember something I'm reading I'll read a part then write a summary. It makes me slow down for a bit and think about what I've read. Same thing with meetings.

Going back later and re-reading the notes is something I rarely do.

You can send yourself signal messages and search them. It's not writing though.

You could write it down, take a picture, and send it to yourself in signal if you must write it.

I use org-roam in Emacs. It is extremely easy for me to find things I am interested in in my collection of 3000+ notes. The key features you want to look for are hyperlinking and backlinking.

apple notes and paper journals.