There are advantages and disadvantages to doing chemo first instead of surgery first. That's been discussed in several other threads.

I'm curious in this case about whether the chemo is really needed "to shrink the tumor" versus just learning about its behavior (response to chemo) and providing a systemic treatment that stops any microscopic spread.

Unless the tumor is huge, or identified as impinging on other organs/arteries/veins, it seems to me (with no medical training) that the standard Whipple surgery could remove most tumors of reasonable size in the head of the pancreas.

How often will the chemo be administered? You will be getting some data during the treatment about how your husband is responding to treatment. My Folfirinox (4 drugs) before surgery was every two weeks. My hometown oncologist tested CBC/CMP every two weeks before treatment, but opted to check CA19-9 every four weeks. (I had my primary care doc order repeat/serial CA19-9 testing at an outside lab so I could get more realtime data and a noise-reduced trend of the response).

In your husband's case, with only 3 months of chemo before surgery, I would request CA19-9 testing with every other blood draw just so you get enough data points to see a clear trend.

They will probably do another scan (CT or MRI) to check for spread before the surgery, as well as see if the tumor is shrinking or invading blood vessels, and that will be another confirming/negating piece of data on how the tumor is responding to treatment. If it has spread, they may elect to not do surgery. If it has grown with no evidence of spread, they may elect to do surgery sooner or switch to a different chemo. After surgery, they will get a first-hand look at the tumor and identify how much remains alive versus dead, and use that to grade the response to chemo. Since they are already planning to do more chemo after the surgery, that grading may also guide them as to whether they use the same drugs or switch it up.

Make sure the surgeon/hospital are planning to save plenty of tissue from the surgery. If you wind up with a recurrence and need second opinions, everyone is going to want a piece of that tissue. Ask them also if they can pre-plan to do a test like Signatera with some of the tissue. That is a DNA-based blood test that looks for evidence of microscopic tumor DNA after the surgery, and gives them another piece of data to cross-reference with CA19-9 and imaging results.

There is also a possibility of using cells from your tumor to create a custom "vaccine" or other treatment that trains your immune system to attack cells with matching DNA directly. The more tissue they have available, the better.

As for the 48-hour take-home pump, that can be rather annoying, especially if he's already fatigued and the pump interferes with sleep. I've posted some of my home hacks for dealing with that pump in other threads, but basically it hangs around your neck like an albatross, and doesn't follow well for side sleepers like me who toss from one side to the other. Securing it to my chest under a tight-fitting lycra shirt held it in place regardless of my sleeping position. There are also newer elastomeric pumps that are much smaller, and possibly also disposable. Ask the good folks at Duke for their recommendations about those.

It's definitely not an easy road, but not as bad as it all sounds at first. Since this was caught reasonably early, there's a lot of reason to have hope. I wish you both the best!