LoRa vs GSM; need advice

Hi guys

A future project of mine will count with a sort of remote control.
The Slave device will be most of the times, closed inside a metal cabinet (Fiber-optics Zone Mutualization Point or PMZ for short).
I am worried about the Faraday's Cage effect, so i ask those of you that have better knowledge of these things, what should i go with?
LoRa vs GSM.
Usage example:
I place my slave device inside the PMZ and go to my freshly completed fiber-optics project, that may be at a distance of up to about 1km ( max).
Then i use the Master device to turn on the Slave device and by doing so i get a visual response on my fiber-optic cable.
What should i choose ?
Pros and cons?

If it really is a complete metal cabinet I would have thought that neither would work reliably unless you can leave the door open during testing or put the receiver outside and feed a wire inside - possibly via the door opening as long as the door closure would not crush the wire too much.

As a left wing idea how about a phone outside the box, set to vibrate when rung, with a simple vibration detector, or a microphone with a bit of level detect circuitry, that connects through the door with a wire to power whatever it is that shines the light down the cable - presumably so you can check the losses.

You are right about the Faraday Cage. Water and Metal kill most signals. This can be overcome by placing an Antenna on the outside - but this is not always practical, and if it is only for testing then probably not feasible as well.

LoRa - Low Power - Long Range (some people say as much as 61km's LoS) - small packets of data at a time - you probably use the 868 frequency unit - but the signal is still influenced by Uncle Faraday. If you only want to switch on the device or put it into some state in the slave area, this is probably your choice as you will not have data costs etc.

GSM (or NB-IoT), will work and generally have good coverage but as in LoRa will be influenced by our favourite uncle and his cage.

Keep in mind (and knowing you - you do know) that you need a driver of sorts on both ends such as an Arduino or ESP !!

Anyway - just my 2 cents - enjoy the project and keep us posted !!

Adding a bit more info to this subject.
I have tested placing a phone inside the closed cabinet and tried, successfully, to pass a call and sms.
The slave will be a 6 laser heads controled by arduino (or one of its brothers) from a 1 or 2 bytes data message.
The aim is to avoid going back an forth from PBo to PMZ to change the cable to test.
With my solution, i connect all needed cables to test, and from each PBo srnd the comand to change active laser head.