It seems to me that before the zombie invasion, no one did things to survive the Apocalypse. Who needs pipe pistols or muskets? Spears, stone arrows, and so on are things that can't be stored in store boxes or safes. Where can craft armor come from in an ordinary person's wardrobe?
The world has been plundered and destroyed. But somewhere there are the usual things that were used in the economy: chainsaws, steel axes, wrenches, etc.
The chance of finding such things should be the same. Factory-made weapons must be stored in safes.
There should be an interest in producing your own things. Now you don't need to produce anything, you just need to do a lot of loot.
On the first day, you can just run around all the houses and search all the boxes that come across. By the evening, there will be a whole set of everything that you can do on the initial levels.
I think that most of the loot at any level of the player should be garbage. But if a player goes around 30 buildings and searches 200 boxes and finds a thing, it must be something good produced before the Apocalypse.