Why would I need to have software firewalls on my devices behind my NAT router at home? The topology is a basic consumer grade one: ISP -> my router (NAT) -> LAN, and vice versa.

If NAT already obfuscates my private addresses through translation, how would a potential adversary connect to anything beyond it?

What "good" would my public IP do for a hacker if I have no ports forwarded?

Is a firewall a second line of defense just in case I execute malware that starts forwarding ports?

I do have software firewalls on all my devices, but that wasn't an informed choice. I just followed the Arch Wiki's post installation guidelines.