More basic, but open source. Obsidian has very interesting features for showing and creating connections between pages, archivy seems to take a more standard structural approach. Links between pages are a planned feature, though.

One of the big features of archivy is how bookmarks work: If you bookmark a webpage, it gets converted to markdown and stored in your knowledge-base to prevent link-rot, which is an awesome feature. I'm not sure Obsidian allows to archive pages this easily.