As per the official notification issued by NIOS (National Institute of Open Schooling) (Notification No 14, issued on 20th June, 2018) -

"In pursuance of the orders of the Hon'ble High Court of Delhi, the learners of NIOS who have successfully completed Senior Secondary Examination of NIOS would be eligible to appear for NEET (Under Graduate) Examinations"

The above statement from the official notification makes it clear that NIOS students can apply for NEET. They can also study in Government medical colleges (selection is on the basis of their performance and ranks in NEET UG exams).

To get complete details about NEET UG Cut offs, you may visit the link - NEET Cutoff 2022, 21, 20, 19, 18, 17 - Previous year Cut offs, Percentile and Scores (careers360.com)

Also, if you want to prepare for NEET UG online at affordable rates with quality features (like AI Learning, Personalized Timetables, Mock Tests, 24x7 Doubt Support, etc) , you may check out this link - https://learn.careers360.com/medical/neet-preparation-material/