You can use any charger from any previous iPhone, iPad or even recent MacBooks. you can even use chargers for other brands of phones like Samsung Galaxy devices.
Any USB charger you have from a previous device is likely to work fine.
The removal of the charger and headphones was done for environmental reasons, and mostly because at this point in time its incredibly unlikely you do not have another chaerger from a previous device you can use with it or other headphones.
Most people just go out and buy a wireless charger or another charging option as well as other headphones even if they were to be included, so it stops making sense to include it.