It’s more commonly called Speed Flying, at least here in Switzerland where its gotten fairly popular in the last two years or so. I’ve seen it a good few times and spoken to a few people doing it. I also have friends that both Paraglide and Ski at a high level but believes Speed Flying is too dangerous!
As far as I have been told you should be able to fly a paragliding wing and ski at a very high level before attempting it. With paragliding altitude is safety, you have more time to get out of trouble is something goes wrong. With speed flying you don’t have altitude on your side and the wings move much faster then paragliding wings which means if something goes wrong its gonna happen faster with less time to react!
Why not try snow kiting instead unless your other half is already paragliding. Of course if she can already do both then there are schools which can teach her. I saw some people being thought in Davos, Switzerland last winter. I think it was the local paragliding school doing the teaching but I’m not 100% sure.