Is it posible to make so a polygon object is detected as a trigger collider when exported to unity?
Nitpick: Tiled does not export to Unity. If you’re using SuperTiled2Unity, that is an importer in Unity, and it imports regular Tiled files.
ST2U doesn’t seem to have any special facility for making trigger colliders, but you should be able to achieve it by using either prefab replacement to replace certain objects with a trigger prefab (not ideal for poylgons that vary), or by using a custom importer that creates trigger colliders when it encounters certain objects. Both of these methods are documented in the ST2U docs here.