Not really. Drawings, pastels, charcoals, watercolors... All should be framed behind glass. Only canvas art (paintings or prints) are usually presented without glass. But even those are sealed/varnished, otherwise they would have the same fate as the unprotected art on paper. Unfortunately papers are not as tough as canvas and not really compatible with varnishes.
Well I have to say that a lot of the time with my watercolors I don't put them behind glass because I don't like the reflections. What I do is to varnish the watercolors using either an acrylic matte or satin varnish like the Liquitex or Atelier varnishes, or, what's much better but a bit harder to apply is a beeswax varnish (available from Winsor Newton or Michael Harding for example). The vanishes are slightly milky when applied but dry clear. The beeswax gives a wonderful depth and protection, and it can be buffed to give a sheen or gloss if you want.
I haven't tried it yet, but I don't see any reason why this couldn't be done on digital matte paper. I think a fixative would need to be applied first - I've ordered a matte fixative from Ghiant, which I should get in a few days, so I'll be able to try it out. The beeswax then gives a very durable finish that can be wiped clean.
The only problem I have with it is that the paper needs to be glued to a board, otherwise it won't be flat, but otherwise it works very well for watercolor papers.
I don't know about gloss, but I'll try it. I suspect that it would be difficult to do it as it's a very delicate surface ... the varnish would probably need to be sprayed on rather than painted on, and you would need a very good spray gun, I expect (a bit like car bodywork spray guns, to give a very fine even spray). I guess that might work: spray the fixative first then spray a gloss varnish.
Robert