All modern NAT routers include a firewall. They don't "act as a firewall too, via NAT", they have both NAT and firewall functionality, even for IPv4. It has been like this for a long time now.

> All modern NAT routers include a firewall.

AFAICT the ER7212PC is not a "NAT router" but just a "router".

Even some switches have ACL functionality for the IP layer, but they're sold as switches and not as firewalls.

Sure, but people still use NAT as a way to secure their internal network, so it's effectively acting as a firewall.