I do something similar and collect notes for speaking with a customer once.
First, all ephemeral notes are in separate folders, so it’s easy to exclude them, move them, or delete them en masse if I want to. No commitments!
Second, I never know what client I may end up talking to over and over again. However, since I don’t know if I will, I may add an evergreen note for the client org and stick the meeting notes there. I DO NOT create less ephemeral people or project notes until it makes sense to do so.
Like the meeting notes and my daily notes, orgs, projects, and people are in separate folders, so I can nuke, move, or exclude them at my whim.
For your processing, it might be cool to process each of your meeting notes right after and pull out interesting or common things and stick them in another note.
I have similar for contractual language where I have a file with all of the “best” language and variations. I copy/paste the entire thing into decks and SOWs and delete what 8 don’t need and edit what needs it. Makes it super fast to deliver high quality content quickly.