Greg Olson (the coach) has a ton of experience that he could bring to the offense
Going in another direction here as Pittsburgh could always try and go with an older route on the next hire. Their new offensive coordinator could be closer to the end of his coaching career rather than just starting. It might not be the most popular route with how the NFL is currently going, but someone like Greg Olson could make sense.
No this is not Greg Olsen, the former tight end that recently retired. This is Olson the coach that has a ton of experience in the NFL on the offensive side of the ball. He is currently the quarterbacks coach with the Seattle Seahawks. He has been an offensive coordinator often throughout his career and could be someone who interests the club with the amount of experience he brings.
Mike Mularkey has connections to Pittsburgh and shares an extensive history with them
Sticking to the older side of things here when it comes to potential Canada replacements. Mike Mularkey has a connection with the Steelers organization and could be a nice get for Mike Tomlin. Right now, Mularkey is out of a job and has not coached in the NFL since 2019. He is a former Head coach in the league and has a lot of other coaching experience.
He is a former player in Pittsburgh and actually held the role of offensive coordinator for the Steelers from 2001 to 2003. It would probably take some convincing, but bringing in someone with a wealth of offensive knowledge would be a benefit to Pickett. Having someone on the staff to control the offense while Tomlin focuses elsewhere might be the best outcome.