I think you are his safe person. If he doesn't do it at school and he does do it with you, he feels safe and loved and can be himself. You can say, I would love to hear about this later, but right now I need to focus on making dinner. It is hard, but sometimes focusing on the why is more important than the what.

Yeah, sometimes there's only so much of this I can handle. I tell my child "not right now" or something to that effect.

I think it's fine to have boundaries, but I know that I wish I could tolerate endless amounts of info dumping.