Yes, absolutely you can get a diploma in AI/ML at a government polytechnic in Nagpur. There are two ways to get admission in this course

1. First-Year Entry: You need to pass 10th with 35% or above.
2. Lateral Entry or Direct Second Year: In this case you need to have PCM in 12th or you need to have an ITI certificate to get admission in lateral entry or second year.

In your case you have 58%, but you don't mention which stream you passed out of, so if you completed your 12th in physics, chemistry, and mathematics, then you can directly get admission in 2nd year, or you can get admission in 1st year if you have the eligibility.

I hope it helps you!!