Try this one: Markdown Viewer. Other than the larger size that comes with being based on Electron, it's all quite good. https://github.com/c3er/mdview

Thanks. It looks pretty decent. And more important is the first one being just a reader/viewer not an editor with preview.

Is there an equivalent tool for Obsidian?

I don't know but since obsidian uses plan text files like Logseq does you should be able to update the code a bit and point LSQ to your directory. My default it opens up the files in your $EDITOR