Two things I’m planning to mess about with for personal knowledge management, both with the potential for self-hosting. First, Grist
Grist is a software product to organize, analyze, and share data.
Grist combines the best of spreadsheets and databases. Grist lets you work with simple grids and lists, and is at its best when data gets more complex.
And Bookstack, similar to Confluence with Markdown support
BookStack is a simple, self-hosted, easy-to-use platform for organising and storing information.