You can’t piggy back one nano into another , if mean plugging over into the other .
Sounds like you are starting from point zero . The best thing is to buy an Arduino and start playing with it so you can get a feel for what’s possible.
Your post doesn’t really make a lot of sense I’m afraid , don’t understand “ page”
The Arduino Nano 33 BLE and IoT are both programmed using the Arduino IDE and programming is similar (using C/C++) to Arduino Uno or others. There are still many differences between the boards for instance the voltage levels are 3.3V instead of 5V.
The both support Bluetooth, the Nano 33 IoT also supports WiFi.
You could write an app that has a single user interface but controls two BLE devices. BLE does not require continuous connections and an app could connect to one device change a setting and then connect to another and change something there.
Do you know how to write an app in iOS or Android?
Note, BLE has limited range you might be better off to use another protocol if you need larger distance. If power is no issue you could use the WiFi connectivity in your house. You cannot run an Arduino with WiFi for long with batteries.
By page I was meaning using the blynk project on the iphone so you could open Blynk with the project coming up to open a gate and roller, but with one serial port you can only use one way of communicating but I would need to boards.
One board would be simple just drag a couple of buttons and a blue tooth to the project on the blynk on Iphone.
Im just starting out Im afraid. I'll have a look writing an app in iOS but...
Voltages I can sort out and have mains at both gate and door.