Agree with Leo not being where he should be development wise. Thank god he goes to nursery as at least they will be doing developmental stuff with him. I would imagine this kid has very little adult interaction or play time with either parent. He’s probably given a load of toys to sit with while parents watch their phones or let him get on with it. It’s vital in the the first 5 years to have that eye to eye contact and get Leo to see how your mouth moves to copy words and language. They need to sit down and play with him (yep it’s a bit boring when you’re an adult) and then talk through play, eg oh look at the lion’s yellow mane, that’s the mane this bit here. Oh I wonder what might happen if we roll this ball, oh look it gets faster, this feels so soft oh but this buts bumpy, can you feel it? Etc etc.
Exploring textures, getting out into the leaves, picking them up, squashing them, printing with them with paint, tipping water in and out of containers. Nothing that costs a lot of money, just spending proper time with the kid!