I'm currently using pngdelphi on win32 and it does work very well, but since it uses the *.o is why I was looking for an alternative.
Paszlib looks very good, but has not been updated in ages. So that would require that I update it to the very latest version of zlib.
Lastly, the colosseumbuilders pascal implementation seems to work partially, or at least seems to be partial as the rendering example that is ships with does not display the toucan image correctly. So that looks like it may need updating as well.

So all in all, at the moment, any way I go, I need to get my hands dirty. Now which path will be the least hassle and will benefit the most people?