Here is the issue.
You are currently illegally in the U.S.
You want to apply to Canada for a work permit in order to accept a job in Canada. For the record, a Canadian employer does not ‘sponsor’ you into Canada. If you have a job offer, you must apply for a work permit, which is a form of temporary residence visa (TRV).

But you can only apply to Immigration Canada from a country in which you are legally residing. If you are not legally in the U.S., you cannot apply for a TRV in Canada. Therefore, you must apply to IRCC from a country in which you are a legal resident.

Your decision to overstay may also create a problem when applying to Canada because Canada and the U.S. share immigration data. All five countries in the FYEY network share immigration data. Nicknamed the Five Eyes, that network includes Canada, the U.S., Australia, New Zealand, and the U.K. A history of overstaying in one five eyes country can keep you out of every five eyes country.