This is still not that many compared to the children going to school. Additionally that's a very heterogenous group, homeschooling their children for a variety

This is still not that many compared to the children going to school. Additionally that's a very heterogenous group, homeschooling their children for a variety of different reasons, using different approaches following different curricula. There is certainly space for companies who want to sell educational products and there are companies already doing so. What that means though is that you already have quite a bit of competition in a market that you're not going to completely capture. If this is your target audience you have a relatively low ceiling and you won't be able to push past it. Additionally you can't scale to different countries or even states that easily. You need different materials to account for different languages, cultures and curricula. You need to account for regulation and a sales teams to approach the various homeschooling groups.