Any leather Glock 26 holster is close enough that it works. No kydex,
leather only. There is also
www.highnoonholster.com who sells the split decision that fits nicely, shown here:
I also know the 5c version from
www.elitesurvival.com fits, but it doesn't have any mechanism to keep the gun holstered, just gravity.
IMHO, the PPS is a fun, accurate pistol to shoot and from what I've seen, one of the easiest/thinnest 9mm to carry concealed. Congrats to your FIL for making a great choice!