+1 Glennewdick
Check out the Audioquest Dragonfly line, notably Dragonfly Red. The form factor is ideal for what you are doing. Plug it in to a Lightning-to-USB converter. The Tidal app on your iPhone will recognize the Dragonfly and treat it as a MQA endpoint, direct-streaming digital to the Dragonfly DAC and yes, bypassing the generic iPhone firmware. I is actually quite good, and can also be used to drive headphones.