Thanks for the feedback! If you don't have a team you're regularly collaborating with I strongly advice against Notion. I built my second brain with Ali's tools (Notion + Readwise + Kindle/Airr/Instapaper) but Notion's top-down structure isn't great for building a personal knowledge management.
Take a look at the combination of Roamresearch + Readwise + Zettelkasten (aka "Roamkasten"). It's an incredible combination.