Germany has their local Tracetogether app called Luca. You can only import EUDCC certs into the Luca, since the SG cert is not EUDCC compatible you need to get it converted to an EUDCC cert. Previously they are pretty lax with the cert scanning, but due to how serious cases are now, the Germans are now more serious about checking your certs.
I was in Germany last week, and saw 2 singaporeans try to enter the restaurant with their Notarize printout. The staff tried scanning with the EUDCC scanner but obviously it cannot be read. So these 2 persons got told to sit outside in the 0 degree cold with the unvaccinated.