6 mo (29 wo) not showing signs of prep for crawling

Hi my baby sits independently, reaches for toys in front of him, he is rolling tummy to back and back to tummy. Bit when facing down plays a couple of min on his mat and then is the end of floor time. He starts crying and that’s it. I put toys at his reach and farther to see if he tries to get on four points but nothing. In other moments I use the breastfeeding pillow as support for him facedown and put toys so he can play and put some weight into the shoulders, but really don’t know what else to do to help him get started.