As far as printing methods without gelatin, there are many -- cyanotypes, platinum, Van Dykes, etc, that are on various watercolor papers, but probably you know this. Direct prints (photograms) would eliminate the need for gelatin based films.
There are polymer plates for other printing processes -- I wonder if that technology could be used for photographic purposes?
Yes, I've heard of cyanotypes, Van Dyke prints, platinum, palladium ,etc..but regrettably I've never tried my hand at making one. I don't print much, perhaps just once a month, and even then it'll just be making prints of 1 or 2 negatives. I'm more interested in an alternative to gelatin in the image capture process, instead of in the printing stage. Perhaps it's time to try wet plate collodion?