Are there any stores that specialize in French Canadian goods, in the Philadelphia PA to Baltimore MD region?
You mean back bacon and hockey pucks? What do you mean by French Canadian goods? Food? Clothing?
Poutaine?
Quebec Nordiques jerseys? (You also need a time machine…)
I don’t know of any and also aren’t sure what products you mean. I would suggest checking out the NJ shore, especially the Wildwood and Cape May areas, especially in summer, as there are (or were within the last 20 years) large numbers of French Canadians vacationing there, for reasons that were always a mystery to me. As recently as the 1980s you could get French language newspapers in the area in the summer, and some campgrounds and motels have BIENVENUE signs and maple leaf flags, but I haven’t been “down the shore” as we say in these parts for years.
Bon chance,
What I mean by French Canadian goods is whatever my wife meant when she suggested this as a theme for Christmas gift shopping for her. She’s got lots of French Canadian ancestors and is an avid genealogist.
One year the theme was Irish and I found a store specializing in things Irish such as clothes, foods, decorations, PC desktop background scenes from Ireland, maps, books, et cetera. Found probably half a dozen things there she really liked. Another year the theme was British and I got her a tea service made in England.
Without knowing much about French Canadian things I’d guess traditional clothes or decorations, foods or cookbooks, perhaps special spices or ingredients or kitchen tools used in that cuisine. Or books, maybe guidebooks, photos of those regions in Canada?
Poutaine - wouldn’t that get cold?
Aha. I don’t know of any such place here as we don’t have any French Canadian neighborhoods or the like. Maybe you could book her a room at a Cape May County motel in July? 
She could meet distant cousins…
At this point your best bet is probably the internet and rush delivery or a roadtrip north…
You won’t need to do much different in terms of decorations, what you will want to do to get the feel of a french Canadian christmas is the food and entertainment.
Look for traditional holiday recipes, turkey is traditional along with other dishes like “tourtière” or more precicely “tourtière du lac st-jean”. I’ve found a link here to such recipes, unfortunately it is only in french… http://www.recettes.qc.ca/noel/
Next step is entertainment. You will next the appropriate holiday music. Search for traditional Quebec christmas songs and throw in a few tacky english classics like “jingle bell rock” (sorry if some take offense to my tacky rating of that song, just my opinion).
Dancing, drinking and some games and the trick is done. Searching the internet with “quebec”, “christmas (or noel)” and other keywords such as cooking, music, etc. should give you a good help in getting your holiday theme going. Your biggest hurdle will be to get a way to find bilingual websites or some translation help.
Good luck,
MC