[shareddreams]

Hello everyone!
I wasn't much of an Android user until I got my new phone yesterday and I want a free ebook reader for my ebook collection, which are mostly pdf and epub. My books are on an SD card. I tried AIreader and the free version of Aldiko and I noticed that they import the book into the phone's internal storage before I can read it, which means I basically have two copies of the file, one on my SD card and one on the phone's internal storage. I don't want that. I installed Cool Reader and it seems to be reading directly from the SD card but it's not able to read pdf. I'm also not getting the Cool Reader option in 'Open with' within file manager when trying to open epubs.
What I want is something similar to how I can read ebooks on my PC, just browse to the file in file manager and click it to open, regardless of whether it is a pdf or epub. No importing and having two copies of the same file. Which ebook reader (preferably free) makes that possible on android?
My phone is a Redmi Note 5 pro.
The reason I'm asking is because my books and documents are arranged according to subject in different folders and I often need to open many of them in quick succession for reference. It is not feasible to import all of them in one reader as there are too many of them. I would like to be able to open them from within file manager, as close as possible to how I do it on a PC.
Thanks in advance!