Welcome to the forum!
To your question: A Shelly needs both live and neutral potential to do his work. And it must be placed at switch SW2 to get access to the lamp wire. Thus, you’ll have to alter your 2 way switch diagram to an “economical 2 way switch” diagram, which gives access at SW 2 to both live and neutral wires:
Above is the diagram for this circuit. Please do us the favour to modify the circuit BEFORE adding the Shelly! You may check the function and after that, you may add a Shelly 1 or Shelly plus 1 according this diagram:
This sketch is identical to the diagram in the forum’s lexicon area:
Right - one wire is missing! Obviously, you’re misusing the green/yellow PE wire to connect SW1 and SW2?!
Another way with three wires only would be the modification of the two switches to buttons:
It is often possible to modify the buttons itself: Adding a small spring turns them to buttons,
