Albumenworks said:
The use of any fixer formulae other than plain sodium thiosulfate (with or without hardener) or aa sodium thiosulfate hardening fixer such as Kodak Fixer, is not recommended. Rapid fix products contain ammonium thiosulfate. While they will fix P.O.P. prints perfectly adequately, they will bleach the image excessively and are likely to produce less optimal colors in the finished print.
There's
lots of good advice on that website, inluding choise of fixer.
I can confirm what they write, I have on one occasion used very very dilute TF-4 as a bleach to clear up the highlights.
If you can print a negative and get decent results using only soft filtration (or grade 0 graded), it will be usable for POP - but maybe a little on the soft side. Pyro negatives are a different matter, and varies a lot with film, developer and whatever. You'll have to do your own testing for that.