Customization in Metro Exodus
The weapon customization mechanic in Metro Exodus is actually pretty similar to crafting, as both are done in either the backpack or at workbench tables. The difference lies in accessing a completely different tab within either the backpack or table and in what parts you'll need to actually make changes to weapons. These parts can be found throughout the wasteland in Metro Exodus, either on the weapons of long-dead corpses or fresh kills. When you come across a random weapon, new parts will be in orange. Players will need to break the weapon down by holding the necessary key or button to take this part.
After this is done, simply go into the backpack or workbench table and access the weapons tab. New customization parts will be highlighted. These can be switched out with other parts that will all add their own benefits (as well as drawbacks) for each weapon. For example, finding and equipping a suppressor for any gun will ensure silence for stealth purposes but the trade off is that it reduces the overall damage of said weapon. It's important for players to know exactly what kind of tactical situation they're headed into beforehand so they have the necessary weapon parts equipped to each weapon.
Weapon customization is one of the most in depth and layered mechanics in the game. It's possible to turn short range pistols into long range weapons with just the appropriate stock and barrel attachments. Or you can go in stealthily with a silenced shotgun, something that won't require too much in the way of accuracy but will need to be used up close for maximum effect. Really, there are dozens of possibilities and it's important to experiment and find the right loadouts that suit your play style. Just remember to pick up every orange highlighted weapon part you come across.
Upgrades in Metro Exodus
Unlike crafting and weapon upgrades, you don't really need to hunt for resources to as much of an unknown degree when it comes to upgrades in Metro Exodus. While various upgrades can be found, only one can be equipped at a time. For instance, you can't have a damage resistant gas mask upgrade and the standard gas mask equipped at the same time. Players will need to pick and choose an upgrade depending on enemies and the surrounding environment. That can be tough considering the unknown nature that comes with playing the game, and it's even more difficult as these upgrades can only be applied at workbenches.
Finding these upgrades comes either from doing main quest missions or during side activities (marked on players maps with a question mark). As Metro Exodus doesn't like to hand-hold, you'll have to find these upgrades without any sort of ping or visual clue like a mini map. Search every area in a bandit hideout or in a dark bunker. Once an upgrade is located for increased ammo in your backpack or relating to the gas mask or really anything, an icon will show what it pertains to. Try not to miss too many of these as it can make late game a little easier, especially on higher difficulties.
There are also brand new items to be found, like the night vision goggles, that won't require a workbench to apply to Artyom's person. Not only are these specific items available to use right away, they can be extremely vital in severe situations. Like everything else in the game, use tactical thinking and patience when traveling through the wasteland and all upgrades will be found and utilized properly.