The big gap I would love to be solved is a, preferably selfhosted, browser based view into my notes. That way I could access my notes from computers you can't or won't install obsidian on.
If it was open source that would be more likely to happen
I threw something together to address that goal. It was really hard to render obsidian-md into html that looked about the same. I started with general MD libs, then ultimately used obsidian-html. Obsidian's MD is not standard at all, though I'm not sure any MD is fully specified since there are so many edge cases.
Do you mean how your notes are connected, and organized? Otherwise, they are plain-text Markdown files. Any app that renders Markdown should be able to do it.
In-fact, I don’t really like Obsidian on Mobile, so I use iA-Writer to edit/view the Markdown files that I managed with Obsidian on the Desktop.
If it was open source that would be more likely to happen