Finding friends on crossplay

Anyone know how to link up with friends on crossplay? I am on Xbox and my brother is on PC/steam

PC players still need to have an Xbox account to play, so just use the Xbox Friends system.

any idea how to link the accounts? He is playing on steam with his steam account.

Ask him to create an Xbox account, and to link it to his steam account. Then use the Xbox friend system to add each other.

ok, the answer I got from the steam guys was that he (the PC) player had to press win+G and then login through the xbox social button. First time ever navigating this, had no idea this was a thing.