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.

For me, it was not being able to use a 3rd party app. Accessing reddit through their garbage app is a painful experience. And unless I find the answer to a question via web search that’s a reddit thread, I avoid it entirely.