Is it possible to generate a PDF version of an EU Digital COVID Vaccination Certificate?

I would be surprised if the answer to the question: How do I upload a digital document? was Take a photo/scan

For me it isn't surprising. If they had asked for a digitally or cryptographically signed document it would be another matter. But they don't.

Canada does not even say "digital document", but "upload digitally" (one might even say it's redundant).

The purpose is for the immigration officials to have relevant data pre-arrival and carry out pre-processing if necessary.

In fact, the same page you linked explicitly says

In ArriveCAN, you must provide: [...]

a photo(s) or PDF file(s) of the record of your vaccination(s), such as receipts or confirmations from the vaccinating organization. These must be in English, French, or a certified translation into English or French.

Either a photo or scan into PDF or an originally PDF file is fine. At the border you will need to provide either a digital or paper copy of your proof of vaccination.

Final determination of your vaccination status will be made at the border. You must bring a digital or paper copy of your proof(s) of vaccination with you.

If you received your vaccines outside Canada, it’s still accepted but proof of vaccination must be uploaded digitally in ArriveCAN and must only be in French or English, or certified translation into French or English.

This strongly suggests they are not after any digitally certified machine readable info like the EU Digital COVID Vaccination Certificate (which isn't really in French or English or any other language) but simply any document establishing you have been vaccinated. A certified translation would certainly be a paper document with an inked stamp and a hand-written signature (certified means it bears the name of a credentialled translator or some local equivalent).

They might not even be set up to read the QR code and clearly indicate that this exemption is not limited to a specific group of countries who have set up a scheme to sign and verify certificates. What they want is evidence a human can read (which is the way most things immigration-related are handled anyway).

I would simply scan a copy of the relevant pages/entries in your yellow booklet or any other document you receive when you got vaccinated. The most important thing would presumably be that it clearly indicates the name of the vaccine (as those are explicitly listed in the requirements). It's probably better if there is a stamp or a signature by a nurse or physician (since, again, nothing suggests they want to rely on the whole digital certificate business).

Incidentally, it should be noted that, by design, a QR code can indeed be copied or scanned. The digital signature is encoded in the QR code itself. So while I don't think the Canadian government expects anything like that, you could certainly create a digital document by scanning or taking a photo of a printout of the code.