Is a gravity or spring damper sufficient for a make up air vent?
This is a good question and I would say it depends. I'm not saying it is impossible, but as you have pointed out these devices operate on static pressure. I am just wondering if it is commercially viable and if anyone makes one that would work in your scenario. It would have to open under very light pressure differences and I don't know of any manufacturer who has one for this purpose. I know this is the same principal as an economizer in a RTU, but they are mechanical.

May be someone more experienced in the mechanics of air flow knows about one.

Good luck.