She was in it with Gus early on.
Los Pollos Hermanos is a part of that big German conglomerate, Madrigal. And Lydia is in charge of logistics/distribution for Madrigal

I guess at this point in the BCS timeline, Gus isn't manufacturing yet. He is just distributing it through the Pollos delivery system.
Lydia is helping him expand.

I doubt anyone but Gus is aware of Lydia. Definitely not Mike