Watch Dogs: Legion has many gadgets, weapons, and abilities to buy in the game. These can be bought from the Tech menu. Not only you can buy these, but you also have the option to upgrade them.
The weapons and gadgets in the game cannot be bought via the in-game currency, ETO. Instead, you need to obtain Tech Points to get them, and there are a couple of ways to get it in the game. First, you can get Tech Points by completing missions. Completing all kinds of missions in the game gives you ETO as a reward.
The second way is to go to Tech Point locations marked on the map and pick them up from there. These are marked by a diamond-shaped icon on the map. If you want to know all the Tech Point locations in a given area, all you need to is make the borough defiant. This will reveal all the locations in the given borough.
Sometimes of the Tech Points are located in pretty tight locations, so you might need to use your Spider-Bot or Cargo Drone to reach the specific spot. Once you have obtained some Tech Points, you can spend them by going to the Tech menu. Buying an item usually costs 15 Tech Points while upgrading them costs anything between 25 to 45 Tech Points, depending on the upgrade level.
We highly recommend upgrading the Spider-Bot since it is one of the most used gadgets in the game. The double jump and cloak abilities of the Spider-Bot are pretty useful and can help you stay undetected.