Basically nobody in Germany uses the chip for identification. I once opened a bank account with it just for the novelty but even the one use should put me into a very small group of active users. Even most government agencies don't offer to use your card.
Actually signing is performed differently and since this summer they switched to a cloud signing process where you don't have access to your key. You cannot get a certificate for a key on the card anymore. Not that anyone actually used that feature.
I mentioned Germany because I've seen Luxembourg-style smartcard authentication as one of posdibilities for submitting german VAT returns online when I cared about such things few years ago and the application involved in that looked mostly the same as Luxembourgh and Belgian one (Oracle Forms, similar UI...)
Edit: otherwise you confirm my suspicion that essentially nobody uses the chip on ID cards outside of Estonia (Slovakia is mentioned due to their recent massive rollout of chip IDs inspired by Estonia, but I assume that actual usefullnes is nil)
Actually signing is performed differently and since this summer they switched to a cloud signing process where you don't have access to your key. You cannot get a certificate for a key on the card anymore. Not that anyone actually used that feature.