During your time in Mass Effect Andromeda you surely stumble upon hundreds, if not thousands of different containers and boxes, filled with almost anything you can imagine - crafting materials, weapons and armors and so on. Most of the "normal" containers will have items of small value inside. This problem, however, can be resolved quite simply.
You can reveal previously hidden treasures, scattered around the surface of every planet you visit. Those treasures can be found without any special means, but it's quite difficult - you need to know their exact location and, given the fact that most of them are extremely well hidden, it's not a simple task. Finding them without any help is almost impossible, as most of them are located in places you wouldn't even think about visiting.
For the locations of the special containers to appear on the map, you just need to unlock one of the many cryo pods. The one you should look for is Reconnaissance, a cryo pod capsule you can find in Military Capsules. With it unlocked, every map of every planet will be updated - hidden treasures will be marked next to Forward Stations. Look for "chest" icons on the map - those will be the treasures you are looking for.
Finally, a thing worth mentioning - the contents of those chests. Inside, in most cases, you will find at least one Ultrarare weapon and even several pieces of armor, as well as numerous crafting materials of different rarity. With some luck, a single chest of that type will allow you to gain equipment worth thousands of Credits.