I’d say steaming there’s a chance you’d do more damage than what it’s worth, same with steam cleaning exteriors , I used to use hot through our pressure washers at my car wash, if you got hot water in a chip could bubble paintwork . I’d say most inportant in doing a good job is the chemicals you use and how strong you make them .
I used to use auto smart brisk , bio brisk.
You can also use g101 from auto smart which cleans better I’d say but doesn’t smell as good, you have to be careful with it cos can damage leather though