That’s what I’m also doing – using a junk old laptop as NAS and it’s been pretty great so far. What would you recommend for expanding the storage of it? It has a SATA 2.5" port and I believe an nvme SSD slot. From past experience, the bigger 2.5" HDDs are slow and have a high failure rate. Maybe it’s just time to ditch the old laptop.
Obsidian is great though, even if it’s not open-source. The stability of alternatives is not at the same level from what I’ve heard.
I know I’m a year late, but maybe someone discovers it someplace else. You still can’t do this – everything syncs to /Android/media/NextCloud/etc