I am within one to two weeks from taking an oath of citizenship in Canada and was applying for work that favours applicants with citizenship. When the application website asks what is my citizenship status, should I click "citizenship"?
Click yes and add a note (if possible) that mentions the date.
Your citizenship status with expected date should be on your resume anyway so you are providing complete information to the potential employer (who may or may not look at it).
If you want to be extra safe: If they contact you BEFORE you get the citizenship, just mention the upcoming festivities to your first contact person.
There is no black and white when it comes to "lying". I think this is one of those situations where being truthful is actually misleading.
If you would have citizenship when you would potentially be working, I think that's a trivially defensible decision to indicate you are a citizen during the application process, because for all intents and purposes you are a citizen.
If you can, you should add a small note somewhere in the application that indicates the expected date of citizenship.
There may be Legal implications for ticking the box that you are a Citizen, when you aren't technically yet a Citizen - depending on the finer details of the application.
It's also generally not a good idea to lie or otherwise mislead on a Job Application.
That all said...
My completely non-legal opinion is that if you've done all the Paperwork, Paid the fee, had the checks done, met the requirements and are merely waiting on the formality of the Oath to the King (still feels weird not saying Queen) and getting the certificate and you have a set date to do those, it's probably fine to tick the box.