Would Papra work for you? I like it better than Paperless-NGX personally, which others have mentioned. But I’ll admit I’m not sure it’ll fit in your use case as I’m feeding it newly scanned documents for mine rather than existing file/folder hierarchy.

Well that’s the thing…I haven’t been able to get any to work yet. Their documentation isn’t great. But the one I’d really like to get going is the multi storage backend. You can then specify hot and cold storage based on the library within Seafile itself, which is pretty great. But I need someone smarter than me to figure that part out 😆