Is the following idea a valid security measure for a simple IOT project?

[bxdobs]

Wondering whether assigning a fixed LAN IP and nonstandard port to an ESP32 along with GATEWAY, DNS1, & DNS2 also set to this same fixed LAN IP would provide an adequate level of INBOUND/OUTBOUND INTERNET SECURITY?

The premise being any Internet inbound traffic attempting to hack common ports won't find the ESP32 and theoretically, the ESP32 shouldn't be able to find the Gateway Router to send any outbound Internet Requests (Cisco Gateway Router LAN IP also non-standard)

The overall intent is to only provide local access to the ESP32 (meaning only devices on the LAN side of the CISCO router would be able to access the ESP32) ... the ESP32 would also be pass protected for local access.

Thoughts?