Logseq to Obsidian.
Logseq's markdown is weird and not standard. Everything is indented and in a list, even headings. I love me some open source, but this is a hard no.
Open your logseq files in a plain text editor and compare with the standard. I spend much of my time editing them back to Markdown.
Syncing logseq is easy on Syncthing. The only issue being that one has to watch out for conflicts by not editing one on one instance before the other sends it/it is received, but that's a sync issue not Logseq.
It was actually a (too oblique) reference to his: I wouldn't join a club that would have me as a member quotation. It was too oblique; my bad.