For Ontario province,
Firstly, everyone has to take G1 license before they can secure a G2 or G license
Secondly, Indian embassy letters are not considered to give G/G2 license. It all depends on a letter from your RTO and that too on their letter head mentioning that, you are good driver and no accidents and no of years of experience.
PS :- You don't need any letter from RTO if want to go for G1 and immediately G2 Road test.
Best of luck!!!