The armory skins (including jet/jump) do NOT work on Sullest. So nothing you have active in your armory will impact your Sullest defense of your uplinks or be active when you attack bases on Sullest. BUT if you are attacking an outpost then the armory DOES work. So if you are taking the Defensive Grid on the Hoth outpost and you relocate to Hoth, turn on the arctic jet/jump skin, and attack - you will have the benefit of that and any other applicable armory benefit.
Officer, RoughTeam, a fun, active, & competitive rebel squad