Keep MuPDF as light and blazing fast as its now, this software is #1 for a fast PDF viewer and for that its perfect now as it is, but i have 2 ideas it could have if you should add something to it: if you flip your phone or tablet in landscape mode, it could switch from showing 1 and 1 page to 2 pages beside eachother. Also darkmode could be a feature to add (up on the right corner). That and maybe opening a few more formats would be all i would ever add, and having borth a larger version and a mini version is a great idea.
Thank you to the devs, this is my #1, that it doesnt do what i mention here means i also have readera for the few times im reading longer pdfs, but if whats asked is added i just need this!