Looking at the stats, If we want an already made option, Theo Hernandez would be the way to go, a defensive minded option would be Cucurella and an attacking option would be David Raum.
Raum's assists (fourth in the bundesliga), chances created and goals makes me feel like he would fit into a Pep team easily, still has some work to do defensively but playing at City that would only get better.
From the youtube highlights, he reminds me more of Zaba than walker, not extremely pacey but very intelligent, loves going forward, very composed on the ball, and takes his time to pick out the best option for a pass.