Shelly 1 - can it be installed in "old installation"

Hello,
I'm trying to automate my house a bit and I'm wondering if there's any chance of fitting a relay in an installation where there's only one 3 wire lead to the light switches. Looking at the shelly wiring diagrams you need a separate constant power supply and a separate wire to the light, and what is in mine is as far as I understand just a break wire going to the switch in the wall.
Above some of the switches I can see there are electrical boxes under the ceiling that can be accessed, so as I understand it that's where all the separation of connection wires happens and that's where the relay would need to be mounted. Is this an incorrect assumption?

The topic concerns both standard switches (I can see there only brown and blue wires are connected) and staircase switches (where the yellow-green wire is also connected to the switch).

My knowledge of electrics is rather poor, hence the very laconic question. I would just like to confirm whether it is at all possible to automate this installation with a shelly, and to call a professional to do the work itself.

Complementing yesterday's question still. I looked in one of those boxes above the switch and found such a tangle there:

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There are 2 light sources in this room, and one double switch (to which three wires are connected - L,N and PE)

Do I understand correctly the assumptions of such an installation that:
- one cable goes to this double switch
- two cables to the two light points
- one cable further into the installation
?

If so, I can easily plug in with Shelly in this place and get the intended effect.

I also assume that similar "technology" is used for all the switches in the house.

The fundamental issue is access to the neutral. If it is in the can then you are home. From the photo it's hard to tell if it is. There should be a group of blue wires connected together and you can't see one. I don't know what's under the yellow-green ones back there. You can only see a piece of blue wire.

If I remember correctly the blue ones connected there are the rearmost ones, but I will check it later today.

It worked.
Just as I thought, there was an N-wire harness at the back of this tangle.
All fixed, old tape changed to quick disconnects, shelly hooked up and it works fine.

Now it's time for the next challenge:

1) Staircase switch - how do I manage this with a shelly?
Do I have to connect shelly to each switch, or is it enough to connect to one switch, setting the mode in shelly to Edge switch (as I understand it, I will not then be able to read the status of the switch, whether it is on or off)?

2) Entrance gate
I have a Came BX operator fitted, which I see in the instructions would also be possible to automate.
Question: what about the power supply? I see that the drive has an output for powering accessories [connectors 10 and 11], but AC
.
In shelly I can change the jumper to a lower voltage of 24-60V but DC.

Should the power supply then be left at 220V AC in the shelly and connected directly from L and N?

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Then just I/O shelly with connectors 2 and 7 of the drive and it should work?

Answering myself to point 2):

It doesn't matter the power source shely if it only supports short-circuit functions (I/O outputs), because these circuits are separated from each other.
Thus, I already have a gateway controlled from anywhere in the world with an app on my phone and integrated with Home Asssiatant.

Time for the lighting on the stairs.... anyone have any experience with shelly and stair switches?

If you haven't solved the staircase issue yet, you plug in behind the second one (the first one gets L on the middle pole, from the second one the middle pole goes to the bulb as standard) and select switch type "edge" - exactly as you wrote.
In the case of a staircase switch, there are no fixed on and off positions because they depend on the position history of the other staircase/crossing switches

chrisjan - Would you provide a photo + diagram of how you connected shelly1 to the gate and which jumpers you have set on it?