I have medium sized black nylon crossbodies from Prada, Lipault and Tumi that are all lightweight and work well for travel. They all have adjustable straps in case I want to convert them from crossbody to shoulder bags and I usually pack them inside a larger tote that I take as an airline carry-on.

You might want to take a look at the options on ebags, they don't have higher end brands like Prada but a search for black nylon crossbody brought up 158 choices that might fit your needs: https://www.ebags.com/search?term=bl...hdr_srch_sf_l1