What you should look for are plants with a dwarf growing habit. For instance, the NuMex holiday series of ornamentals, or the ever popular rainbow varieties. The NuMex ornamentals can be found from the source, here (link is to Twilight, but browse around for their many others). They’re all dwarf types well suited to very small containers.
There are other peppers with a dwarf habit, but these are the ones which immediately spring to mind.
Look up Apache pepper. It is a Dwarf plant with small leaves that is very hardy. I've grown in the garden and in a pot inside. Produced pods both ways.