9 month old not grabbing

My 9 month old boy can sit unassisted but he will not grab a toy or something that is handed to him. He may touch it but will just drop it to the floor or look at it uninterested. He is also not attempting to crawl or pull himself up. He will just sit there, laugh and clap his hands and make sounds. We had his well check today and the pediatrician expressed concern and referred us to ECI. I reached out to them today but they said it may be a couple weeks before we hear anything. Has anyone had this issue and figured out what was wrong or how to help baby? Any tips on how to help him progress in the meantime would be great.