I don't know where your shopping but Rainbird indeed has emitters with different size flows from .5 gallons per hour on up. Other brands also have emitters of different sizes. Go to a pro irrigation shop.

Good Day ...

I've used an adjustable emitter called a Shrubbler in pots.

It's discussed a little over halfway down this page.

There are different size emitters and adjustable emitters. You can run one line to the pot and split it right at the soil in the pot. That's what I do with my big pots. I prefer the different size emitters to the adjustables. But, that's just me. The adjustables do seem easier to find. The .5 gal. ones are hard to find. I wouldn't have half as many pots if I didn't have that drip system!