Context - I carried a Keltec P32 in a Don Hume back pocket holster for over a decade plus. Usually it was a backup to a primary, larger pistol, but it was glorious for slipping easily in back pockets of jeans and slacks. Even had it with me when I got married. As noted, many drawbacks to back pocket carry, but it seemed plenty viable in 20s and early 30s. My anticipated use was also usually for a rather proactive, surreptitious draw, not a reactive draw - I am really doubtful to their value unless you have a serious tactical advantage.
Relative to the OP’s ask -
First, single action in the back pocket makes me uncomfortable even in a quality holster. The 938’s safety lever is small IIRC, but I could foresee some butt scooting potentially disengaging the safety. Without a grip safety, the 938 is beyond my safety tolerance risk. Back pocket is DAO zone for me.
Second, I have tried slipping a larger gun, including J Frames with pocket holsters, into the back pocket. To me, they are obviously a gun and the takeaway risk is unacceptable. The 938 is small and might straddle the line, but with the size/steel frame I think it will print badly in just about anything less than brand new Carharrt work pants. I am smaller framed guy, so YMMV.