Hello,
Yes, you will be eligible for NEET PG as the guidelines say that internship must be completed on or before March 31,2021. So, if you finish your internship by this date you can apply.
Yes, you can prepare for NEET PG during internship but you must put in more effort as you will have to balance working as well as studying. However it is not impossible. You can do it. All the best.
For more information refer to the site
https://medicine.careers360.com/exams/neet-pg
Hope this helps.

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