What matters most is how big the smallest hole is.
Something like this would probably work fine.
https://www.amazon.com/Fortress-Caliber-Metal-Ammo-Can/dp/B01LYVW7DQ
Or this.
https://www.amazon.com/Farmhouse-Bread-Box-Saratoga-Home/dp/B0912YZ523
Or this.
https://www.amazon.com/Durham-226-95-IND-Rolled-Individual-Height/dp/B006WQAT7A
Whatever you get, test it. Put the keys in the box, go out to the car, and try to start it.
If the car can't read it from a few feet away, attackers likely can't either.
Minimum IMO is a cheap B6 style charger on Amazon. These have been rebranded countless times, but they all seem okayish.
After that, I'd say save your pennies for a bit until you can get a decent dual channel charger, which is basically just two independent chargers in one box that share an interface. They're generally a better price than two chargers of the same quality, and it's really nice to be able to charge two batteries at once. When buying reputable brands, price is proportional to the charging throughput. The first one linked below, for example, is 50W per channel, and wouldn't be powerful enough to concurrently quick charge large 4S+ batteries, but it's plenty for the 2S and 3S batteries you'll likely run at 1/24 and 1/18 scale. The second one is 80W per channel, so you're paying for a bit more power.
I also recommend picking up the following:
Generally you want to store you batteries at storage voltage, or about 3.8v per cell, and then charge them up when you're going to use them. Once you've got a bunch of batteries, it's nice to have the little charge checker for when you forget which were charged, or whether you already put them back into storage charge. Your charger will have a setting called Storage Charge that will do this for you. Keeping them in a LiPo bag, inside and ammo can (with the ammo can's weather seal removed), is generally the best value fireproofing for these little batteries. Also, if your battery ever smokes, puffs up, or the cells go way out of balance, you'll want to dispose of that battery. Lots of vids on YouTube about how to do that safety, and many local hobby shops will also take bad batteries and do that for you.