And here goes the problem with personal tastes......
I've found canned (and jarred) duck confit that I've bought in France to be quite mediocre and I was realy quite surprised considering it's one of France's famous dishes and because I've heard rave reviews about the canned variety. There may be some truth in the difference between brands but I've tried several and none of them were any good.
Most French supermarkets have a large section devoted to pre-made foods and there's a lot of variety, from roasted chicken, trays of lasagne, parmentier potatoes, dauphinoise potatoes, roasted vegetables, curries and so on. I would choose from that counter rather than a can of duck confit. I don't recall seeing duck confit on the ready meal counter but that's not to suggest that it's not available somewhere.
You will find takeaways (takeouts) such as Chinese, Indian, Thai etc as you'll find anywhere. You'll probably not find yourself asking for a doggy bag in a restaurant as undoubtedly there won't be anything left to bag up as portions are adequately sized.
Whenever I've stayed in France it's been self catering, the majority of our restaurant meals were lunches therefore dinner was usually a light affair or something that didn't require much effort (or even a Chinese takeaway, it's interesting to see the differences in a cuisine between various countries) and there's not a lot that can beat a good baguette, some cheese, charcuterie, pate and an excellently priced bottle of wine which requires pretty much zero effort to prepare.