What's the question or issue?

acrobat reader says it supports both pdf and ps.
preview (mac) says it supports both ps and eps after an automatic conversion to pdf.
No idea if either one can export or save as postscript. But if you have a postscript printer driver, I suppose you can print it to a file. Is that even an option anymore? I have no idea. (I checked preview, there was no option to export to ps)

If you want a converter to ps, I guess you can check out xpdfreader, I don't know anything about it. It's open source and free. xpdfreader.com

I haven't done anything to generate a postscript file in decades. Everything is pdf now. I had a brief time with a postscript printer in the early-mid 90's which I ended up returning.

-David