zadam/trilium
github.com

Build your personal knowledge base with Trilium Notes - zadam/trilium

Hierarchical PKBs seem less popular these days, but this is a pretty snazzy one

Personal Knowledgebases
!pkb

    From the commonplace book to the zettelkasten to the personal wiki, and everything in between. Technology-focused content and practice-based content both welcome. While we’re still small, screenshots of your notes that you’re particularly proud of are also welcome!