FWIW, as of 2023, Preview no longer supports postscript files. Which is pretty annoying if you like to hand write postscript.
From that Apple note, a nice to know is that you can directly drag a ".ps" file on to the printer queue and it will be printed (assuming your printer talks postscript!):
If your printer supports PostScript, you can continue to print .ps and .eps files by dragging them into your printer queue: select your printer in Printers & Scanners settings, click the Printer Queue button, then drag the file into the printer queue window to print it.
I've just installed the ghostscript suite, which includes tools to convert ps files to pdf files. There're options for installing here.
I took the brew option: brew install ghostscript.
There's no "ghostscript" app or command installed, but you get a whole bunch of tools, and one is ps2pdf that will take your ".ps" file as an argument and write a similarly named ".pdf".