Same answer for Sniper Teams, they don't break up into individual units, nor do the Heavy Weapon teams.
If you want an example that breaks up, just use the Valkyrie. At any time before it is "set up", that unit is a single unit of three models. Once it is set up, either during deployment or via the Aerial Drop ability, they split into three individual units. Thus, if deployed off the battlefield, they are single unit for the purposes of Tactical Reserves, and if they are deployed on the Battlefield during deployment, they are a single "drop" but count as 3 units for the purposes of Tactical Reserves, as each are "treated as a separate unit for all rules purposes."