Just to add my $0.02 here.
Tried various apps and systems and what not, and Obsidian is checking a lot of the boxes for me.
But the one constant problem cutting across all of them is the “gardening” or “weeding” of the sea of notes that accumulate over time. It becomes a question of how much time is needed to ensure they remain (1) discoverable and (2) “relevantly-connected”.
Something that works in Obsidian’s favor (IMO) is its open format; I’m confident of being able to find and change the “internal structure” to my whim.