Is there any such certificate or something even remotely like this awarded and recognised in Europe to undergrads who do, say, chemical engineering but want to show they have some core physics knowledge as well?
The University of Oldenburg in Germany offers an undergraduate program in Engineering Physics if that's what you mean. Anyway, this is just an example as there are similar programs offered by different universities in Europe. I suggest using this website: https://www.bachelorsportal.com/
I'm not sure what you mean by "certificate". There are many universities in Europe that offer BSc/MScs programs in Engineering Physics. The curriculum can vary a LOT between countries and even different universities; at some universities it is essentially an electrical engineering program with extra physics (focusing on e.g. semiconductor physics of photonics), and in other places it is physics with a lot of extra engineering courses (mainly EE) which tend to come in very handy if you want to pursue a PhD in experimental physics. In Sweden (where I studied) many (perhaps most) people who go on to get a PhD in physics have an MSc in Engineering physics (and this includes people who go on to do a theory PhD in say string theory)
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