SHD Tech is the game currency or the Perk Points that players can use to buy themselves new Perks. These can be bought in the White House AKA at the Base of Operations.
To upgrade any skill, it has to be bought first and then its upgrades will automatically show up on the menu. These upgrades will increase your chances of winning in the battles as now you have more polished and modified skills.
The Division 2 SHD Tech Farming
You can find SHD Tech Cashes hidden around in different areas inside chests. You can explore the areas or you can interact with the tables in the Safe House that will show you the hidden SHD Chests on the map.
You can acquire SHD Points or high-level cosmetic items from the Phoenix Symbol on the map.
Another way to farm SHD Tech is by simply leveling up in the game. As you level up in the game, you are rewarded with 1 SHD Tech each time.
Completing the mission that you get is also a way to farm a high amount of SHD Tech as well. Complete the mission and you will be rewarded SHD Tech according to your difficulty level in the game.
After you finish all the challenges in the Main Story, you are giving some additional Side Missions. You can farm up to 5 SHD Tech by completing these Side Missions. These are all the ways to get your hands on SHD Tech.
Use these wisely when unlocking Perks with them as collecting these SHD Tech Points is nearly not as easy as shown above and will take some effort and grinding before you are rewarded with them.