I am mainly going to be using this is my oneplus phone and tital, I use this dongle.

https://www.amazon.com/gp/product/B0828TV3XH/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Is that good enough or is there something else I need?

I have one of these machines. I put Chrome OS Flex on it, which works quite well, but the sound does not work, as you say. Since I mostly use headphones, I simply got a very small USB C DAC (https://www.amazon.com/gp/product/B0828TV3XH $15 for two) which works fine for me.