I just got this set up last week too. Same setup with caddy on a free oracle vps, tailscale on vps and home pfsense router, tailscale on pfsense advertising routes (private IPs of my docker hosted services).

CGNAT sucks 🤮

Have you tried creating a subdomain for the camera and then proxy that to your camera? Ie, camera.example.com [CNAME -> example.com] -> nginx -> 192.168.x.x? Then embed the camera.subdomain.com in your WordPress however embedding videos is done?