Gravy

This probably won't help you much but in my opinion, the short answer is no. The drippings you get from a sous vide roast are not like those of a roast done in the oven. You will get what is a bloody residue which others have used for gravy but I don't think you would want to use it for popovers. Don't forget that a roast cooked sous vide will not be brown, you need to sear it after it has been cooked.

I've also found that the liquid left in the bag will coagulate if you try to make gravy out of it. It turns into a lumpy unappetizing mess. I imagine there might be some creative way to prevent this, or maybe you can blender it down. But it definitely isn't the equivalent of adding broth to a pan after searing, which is what I'd suggest doing post SV/searing for your gravy.

I haven't given up yet... The previous writers are right. The fluid in the bag is not like the drippings in the bottom of a roast pan. They have lots of protein that will coagulate when heated. My first few attempts were visually unappetizing although the smell and taste was not too far off. I recently cooked a pork country rib for 2 days and then tried something new with the juice. I took some of the juice and mixed some corn starch (I think you could use flour instead). The rest I put in a pan and added about 2 grams of sodium citrate. This compound is used to maintain emulsions. (I made some amazing mac-n-cheese sauce with just milk, sodium citrate, cheddar, and salt. Creamy and wonderful flavor. Going to try Havarti next.) Wisked the sodium citrate in, added the corn starch mixture, and then heated to a boil while whisking. The gravy looked right, smelled right and tasted right. I'll need to experiment more, but I'm hoping this approach pans out.

One thing to note... this still isn't quite like the gravy from your childhood. Remember that that liquid from the sous vide bag has never been over 140F in my case, so it is missing the complex compounds formed when getting proteins hot...

Or you can cheat and make gravy from reduced beef stock....