Will this work with a Glock 19 with a light? Thx

The holster wraps around the barrel/trigger. As long as the light is not too oversized where the width is that much greater than the width of the barrel/trigger area, then it should fit just fine. You can see examples of how the holster wraps around the firearm. https://cdn.shopify.com/s/files/1/1527/5001/products/UPW_GRY03_detail_1024x1024.jpg?v=1626830543

Anyone know if this will fit and hold an m&p9 shield with tlr-6 properly?

Should..they’re adjustable, put my G19 and HK vp9 , G43 in mine

Hi will this hold a glock 19 with the plastic holster?

UPW Universal Pistol Wrap has a circumference of 8". Which means the widest part of any object would be approx no more than 2.5" from one side in order to fit properly. Please make sure your holster is within those specifications. https://www.maxpedition.com/products/upw-universal-pistol-wrap#tabs-4