DAC circuitry is a solved problem, any USB-C DAC will do. Apple makes one. Even their lightning adapter got good reviews.

They are $10 each. They can be attached to the end of your headphones and forgotten about.

The USB DAC i got with the iPad is not great. I have tried a couple on my phone, and about half of them are actually not great.

Even worse: cheap usb c headphones all have shit DACs and will perform worse than cheap 3.5mm headphones.

I've seen analysis that says the lightning dac from Apple is actually great: https://www.kenrockwell.com/apple/lightning-adapter-audio-qu...