I am interested in knowing which natural categories of its representations the etale fundamental group of a scheme can be recovered from.

Suppose $X$ is a scheme. Let $\pi_1^{et}(X)$ be its etale fundamental group. Thinking along the lines of Tannakian reconstruction of a pro-algebraic group from the category of its representations over some field $k$ as the automorphism group of the forgetful functor to the category of $k$-vector spaces, I am wondering if there is a natural category of objects associated to $X$ (e.g., sheaves) on which $\pi_1^{et}(X)$ acts and from which it can be reconstructed in a manner analogous to Tannakian reconstruction.

Also, what role does the choice of the field $k$ play?