If you have/had your calibre library FFS backup on an NTFS formatted memory stick, and you plugged it into the OTG adapter, then I would think you could use Calibre Companion's Cloud (CCC) feature to access it on your tablet? See ==>>
What cloud providers does CC support?. Note the last one - local storage.
Edge is part of the furniture, so might as well use it. All I need for calibre server is a simple tabbed browser - Mosaic with tabs would do. Just not sure if MS's use of Edge for their 'apps' might interfere with my use of it for calibre server - hence maybe Midori or similar. But I'm waiting to see what Calibre 3.0 includes before I go any further with replacing Chrome
BR