Does anyone else have a child that can’t play by themselves or entertain themselves?

My son is almost 3 and cannot play by himself at all. All day he chases after me asking for something. I have other things I have to do, I have to clean, cook, eat, and care for my 7 month old as well. But if I don’t give 100% of my attention to my oldest 24/7 he cries and whines at my feet all day. I wanted to send him to preschool this year but I can’t because of Covid. How can I teach him to play by himself more often? I do play with him, for hours a day, but I can’t CONSTANTLY entertain him.