I recently applied for a Schengen Visa (from: Canada. First entry: Germany) and waiting for the result. Even with the visa, I'm still a little bit nervous and started making up different scenarios in my head. Let's say I get approved, I have taken at least 2 covid vaccine shots, I have the negative covid test result 3 days before travel date. What would be the possible causes that might prevent me from entering the country?
You should be fine.
Travel from Canada to Germany is at the moment relatively easy.
Canadian residents have unrestricted access to Germany (https://www.bmi.bund.de/SharedDocs/faqs/EN/topics/civil-protection/coronavirus/travel-restrictions-border-control/travel-restriction-border-control-list.html#f13919566)
It's unclear why you did apply for a Visa. Canadians don't need on for Germany unless you want to stay for more than 90 days.
Canada is also NOT on the list of risk, high-risk or virus variant countries https://www.rki.de/DE/Content/InfAZ/N/Neuartiges_Coronavirus/Transport/Archiv_Risikogebiete/Risikogebiete_2021-08-20_en.pdf?__blob=publicationFile
Since you are fully vaccinated and are not coming from a high risk area you don't even need a Covid test (https://www.lufthansa.com/us/en/corona-tests.html)
What would be the possible causes that might prevent me from entering the country?
- We live in a fluid environment and rules and regulations change quickly. Tomorrow's rules may be different from todays, so I would recommend to stay up to date.
- The airline will check your papers during check in. Since everything changes quickly they may not be fully up to date and may ask you for things that you actually don't need. Even though it looks you don't need a Covid test, it doesn't harm to have on ready
- Keep in mind that Germany requires a PCR test taking not more than 72 hours before ARRIVAL (not departure). This can be tricky if you have long layovers before you arrive. They also accept Antigen tests (rapid tests) taken 48 hours before arrival Make sure your test fits the time requirements and you do the time zone adjustments properly
Overall Germany is relatively easy going entering Germany is much less of a rigmarole than entering (for example) the US.
for some reason I might not enter the country and have to flight home
That is very unlikely. If things go sideways, it typically happens at check-in. If your paperwork is not sufficient, the most likely scenario is that you will be denied boarding and can't get on the flight in the first place.