I know it's not "boyish" but what about dress up stuff and/or a kitchen set with food? That keeps my kids busy for a long time. We very often play "store" with the food and their shopping carts (another idea) or picnic or restaurant. Now that DD1 is writing she drew up a whole menu with prices and drawings and words of the different foods. It's so cute! And it's easy for a preggo to play because you can just sit there and let them cook you food
My kids also have a play tent that keeps them busy but sometimes they get too wild in it....