If Gvardiol falls through for whatever reason, I think these could be 2 great options.
Schlotterbeck’s tall, quick, good in the air, bags of goals & assists. About as good as you can get in a ball-playing CB. Left-footed. Apparently gave a few penalties away for Germany but hasn’t conceded one in the league yet. Statistically the best tackler in the league and has been in Team of the Season twice at only 23, once for Freiburg, once for Dortmund. Seems like a quicker Laporte.
Next is Giorgio Scalvini from Atalanta. 6ft4. Left-sided CB but right footed. Can also play DM. Two good seasons at only 19.