Is this overkill?

I am on Wi-Fi and behind the IP’s routers, have a router myself, plus Comodo.
Is this overkill? does it affect bandwidth?

No it’s not. Comodo will give you inbound/outbound protection.
Router is not (by itself) a security hardware, just an Internet share.

Do your routers perform proper application outbound filtering? I’ve not heard on this. But, if they don’t, then that’s usually one of the main advantages of a PC-based software firewall over a router-based hardware firewall. In simple terms, there is control over what your system and applications send to the Internet. Hardware firewall’s don’t usually know what any given PC is doing in any detail. But, hardware firewalls are a great front-line defence and are very good at rejecting inbound unsolicited connection attempts (without any resource cost to you).