that is why you vacuum seal your kit then put it in an otter box.
I’m not sure what the original posters intention is, other then to have a way to start a fire after everything being wet. (is it for a single use or did he want something he can use more then one time before he’s back home?)
But I would guess that vacuum sealing is a home operation only.
How repeatable is vacuum sealing in the field? My guess not too much. A fire steel and some nail polish are very repeatable. As are the wax cardboard and matches I posted above, or some kind of watertight container. But I would always worry about a container getting some water in it. Something about a guy named Murphy.