I have a Samsung Galaxy Tab A SM-T510 10.1" tablet with Android version 11 that I use for an ereader. I have an app that does a wonderful job with my epub's but I also have a lot of books in PDF format and that's where things get dicey. I've looked at a lot of PDF readers and if the pages aren't being displayed so large that I have to scroll up and down them to read them then it's only using about half of my screen space to show in just one page format.

Does anyone know of a really decent free or decently priced PDF reader that will display two page format with no scrolling up and down to read? I've about gone crazy and would really appreciate the help!
Maybe try KOReader?
You download apk direct from Git. I use it on Elipsa for PDF and also on Android based Mars eInk, but for epub, but the PDF works on that.
I use Xodo on Lenovo Tablet for PDFs only.
Don't know the reader market well, but would recommend a tablet for fast scroll and zoom. KOReader's main PDF engine comes from k2pdfopt. You may want to check that out if you haven't yet.