What's the best controller for steam link?

Basically i want to play my steam games in my phone or tablet but without using the touch screen. I want something that would surround them like the controllers of a switch surround its screen.

I want it to be easy to configure, to work in both phones and tablets and that is not excessively expensive.

Anyone has any suggestions?

@nirgal: So you want third party brand mobile joycons?

Check out the brand Razer, I believe they do what you are after and are well reviewed as a product of quality. If you buy one make sure you buy the correct one, as the IOS Universal Mobile and Android models are different. They also sell joycons for various tablets.

@RSM-HQ: thanks a lot!