Are you interested in porting apps ? Here is one
ezPDF Reader. Android app. It is not open source. If ported that would be the end of all our problems. I guess you have better chances to port Android itself
Above you should be more specific, you are referring to open source apps
Rather than porting apps I would vote for improving the existing PDF reader
I believe all that is needed is in the git repository. Too bad I do not have the skills to do that.