When a request comes in to print complicated shapes, with less common materials, one needs to reflect and test. But in general it yields usable results.
Orthopedic shoes to be printed in Polypropylene (PP), without internal supports or structures? The best option is a belt printer. The inside is support- and infill-free, and the outside only needs supports under the sole. Tests of the shape first using petg, to eliminate the material factor. Once validated, tests can run with the more difficult material.