It's not too complicated to see how he'd fit the team, as Pep has been asking Walker to play wide very often this season.
We have even often asked both fullbacks to go up and wide, let the wingers go in midfield to crowd it with 5 players. Pep usually does this against high press teams (Newcastle).
He would basically be a winger who happens to defend as a RB when needed.
He may not be as good defensively in transitions like Walker has been for us, but Pep would definitely need Stones or Akanji as the RCB to help out there.
Allows the RW to move inside, whoever that may be, Savio, Foden, Bobb most likely.
I still personally prefer our system with wingers out wide, and no fullback holding the width, but pushing a CB into the midfield, Stones or even Akanji has gotten better at this, and I think Gvardiol could be a superstar in this role with some of the things we have seen him do.
And Frimpong could still be bought and useful as he can just be a fast dynamic winger to join in the likes of Doku and Savio.
This allows Grealish, and Bobb to play more inside midfield spots with Foden and KdB.