if the adapter has a DAC and amp inbuilt then it will work - but the Poco will not pass through an analog signal over the Type C USB - and while the Poco does have OTG capability it will not provide power to some power hungry external devices like DAC/AMPs that work off USB like the Nuprime uDSD or ifi iDSD .... but lower power models like the audioquest dragonfly do work

in terms of your 3.5mm input try connecting your earphones/headphones while the phone is not in a case - those sometimes get in the way and when the connection is not solid then the Google assistant keeps opening and interfering with playback