I recently bought two Amcrest cameras (4k[1] and 1080p[2]) and did not need to download an app or make an account to set them up. Both just plugged in to a PoE cable and I was able to access them individually on my WAN by typing in their IPs as well as use them on NVR software.
I use Amcrest cameras with external routing blocked. Integrate nicely over RTSP with my favorite apps and Home Assistant.
For Wifi ones, like my doorbell camera, I had to use their app to connect them to Wifi but subsequently block their internet access with no issues. I can still react to events and control settings using Home Assistant and the Dahua HACS plugin.
1: https://a.co/d/8k1BWBY 2: https://a.co/d/4a0xnPP