These days most people who want that kind of security also have cameras and they just use the motion alerts from the cameras. These tend to be more reliable than the PIR sensors. The price on cameras has come down significantly in the last few years as well, and there are a number of options.
Integration with SmartThings is trickier, but there are multiple choices there as well. Arlo and Ring have official integrations for some (not all) models. Blink and Wyze are less expensive devices, and you may be able to get some integration through Alexa routines. Other brands may require IFTTT or other methods.
This thread has some examples of how people use the motion alert from Ring cameras with smartthings.
2020 Rundown: Ring Products and new V3 App?
Anyway, just another possibility if that might work for you. 