You can model it as a spring, but it's not a spring in the slinky sense - it's just a thin piece of material whose electrical properties are affected by tiny changes in stress/strain.

Its operation fundamentally involves (near infinitesimal) movements, but then so does a cell phone pole. I don't see what we gain with debating its "solid stateness" (especially when hedged with "effectively"). Maybe you could point to some effect that this distinction implies?