In Heidelberg, Germany this week. Frankfurt Airport on arrival, no checking of vaccination status.
Hotel (Marriott) asked for vaccination certificate - visual of my international certificate on my phone was enough,
Also, hotel staff insisted I change to N95 mask (I had blue surgical mask handed out on Emirates). Luckily I bought a pack in Dubai...
Pubs/bars in Heidelberg was mixed (some strictly asked for vaccination proof, others did not - but that seems to correlate with how late in the evening it was!
It all cases, my international certificate on phone was fine - they tried to scan and when it doesn't work they check the last vaccine date visually. One asked for other ID to prove I was not EU citizen.
Checking in at Frankfurt on the way home tonight was asked for vacc certificate (I showed paper copy) and DPD (I showed phone app).
Hoe that helps