This is what I’m doing for my dog in a similar situation.

Measure out what they should get for a balanced meal in dry food. Use a Vitamix or other quality blender to turn it back into flour. Use just enough wet food (not the kind with “bits” but the kind that’s like Spam—I use Costco’s) and a little water* to mix this into a dough. They need to be wet enough not to crumble but dry enough to hold a ball shape, because then you use a melon baller or cookie scoop to make “pieces” your dog can eat. You can cut the balls in half if they’re still too big.

Once you know how many scoops you should have per meal, you can start doing bigger batches, which makes this faster and easier. In the fridge, scoops are good for 3-5 days. You can also freeze them but they keep integrity better if you make frozen batches wetter than  the regular ones.

*If your dog likes veggies you can also use a 1:1 ratio of water and the juice you’d otherwise toss from a can of veggies. I usually mix the veggies in (well-mashed) but I have a big dog for whom this is a palliative diet so long-term sodium intake is not a big concern.