Maybe I should elaborate a bit.
At one time, Ferrania was a large company and part of the 3M family. They had plants in Minnesota, Rochester and Italy as well as several elsewhere. At present, they are in bankruptcy proceedings in Italy, but are still producing film. So, they are dwindling rather than vanished. Sorry.
As for specialty papers, if photo paper and film support were easy to make, I would expect to see more than just two or three major producers. Schoeller in Germany suppies Kodak WW and Central and Western European companies. And, FYI, to supply WW paper supplies for photo use, 900 ft/min is SLOW! Width is important as well as is 'press'. Photo paper is, in some cases, over 80" wide hot press. RC paper takes several additional operations to produce.
Papers contain stabilzers and humectants to prevent cracking of the support during aging. Remember, the papers you are talking about may be used one time and discarded, photos are expected to last.
Same goes for film.