All fair points but I just see it differently. I think Kimmich is more aligned with the present and (admittedly more short-term) future needs of the team than any of the others you mention.
The main reason for that is tactical. I think throughout Pep’s time with us, we’ve always been at our best with a defender stepping into the centre of midfield (Delph, Zinchenko, Stones). Whenever we’ve dabbled with wingbacks (start of 17/18) or wide, attacking fullbacks (Mendy in 19/20, Walker than Gvardiol last season, Gvardiol this season) we’ve been nowhere near as good. Aside from Stones, Kimmich looks to me like the best defender-into-midfield-stepper anywhere. That he gives us another option to play more orthodoxly (and at a high-level) as a DM/6 is obviously a bonus.
So I suppose it would look something like this:
———Khusanov—-Dias——Ake——-
(Akanji) (Stones) (Gvardiol)
—————-Kimmich—-Rodri———
(Lewis / Luiz)
That, to my mind, goes back to giving us a proper defensive structure, and the ability to actually move the ball forward properly through the central areas of the pitch.
The other thing that appeals about Kimmich is, precisely, his experience, leadership and game/tactical intelligence. If, as seems plausible, Gundogan, De Bruyne and Bernardo all go in the summer, that is a hell of a lot of footballing intelligence to lose, which is, ultimately, always going to be critical to any Pep team. Kimmich would help mitigate those losses, and he’d be able to step straight into the leadership group with Dias and Rodri.
I obviously take the point on the financial outlay, but I think it clearly worth it.