They were fun and the results could be great. I'm glad I had the experience.

Sadly, there is no replacement. Type R paper went away first. Both the print material (the glossy was all plastic so I hesitate to call it "paper") were made by Ilford. After the company split into "two Ilfords" it was made by the Swiss one, no longer with any connection to the very much alive Ilford we know in black and white.

Besides reversal processing RA4 the only conventional darkroom method of printing transparencies that I'm aware of now is to make internegatives. People (but not me, I haven't tried) report good luck using Portra 160 now that interneg film is long gone.

The most practical is to just scan and print digitally, either ink jet at home or via lightjet of various sorts at a lab.