do i need the DJI osmo pocket 3.5mm adapter for a microphone to work? or can i just buy a 3.5mm mic adapter for usb c on amazon since i need one and they're all out of stock.

I have not gotten my Osmo Pocket, yet, but:  Since it is made for usb-C phones, my guess is that it is a standard USB C adapter. And if not, you have on to 3.5 for your phone ;-)

Aside: You have yours, now?
Go to a shop where you can test it!

Hi Electricfuse, Osmo Pocket only supports DJI official 3.5mm adapter if you would like to connect to the external mic, please leave your email in our online store and we will send you a notification as soon as we have the item in stock.