How to keep 4 month old entertained??

Not sure if anyone else is having this issue. This is definitely and fun age but I’m finding it also difficult. The babies can sit up, but only with assistance so you have to be there with them. They cant crawl. Etc. My son hates laying in his doc a tot and his swing. But I can’t hold him 24/7! lol.

He loves sitting up assisted in my lap and trying to touch his toes. He also loves grabbing toys but can’t retrieve them. So I have to always be there to help to them back in his hands. He has a play mat but sometimes I think he gets over stimulated 😒.

Anything you guys use to keep your 4 month old occupied when you want your hands free? Lol. My son loves sitting up but needs assistance so I’m wondering if those assisted sit-up chairs are good for him. Maybe something with lights or moving objects? Idk...