In addition to SAP schools, NROTC has a prep program of its own. Called the NROTC Prep Program, participating NROTC schools will pay for a year at their school with a 4-year NROTC scholarship awarded at the end of the year. There are 22 participating schools all over the country. The details can be found at
https://www.netc.navy.mil/Commands/Naval-Service-Training-Command/NROTC/NPSR/
You can get more information from the NPP coordinator at the colleges of interest.
In addition, students enrolled at Military Junior Colleges, if they meet the NPP standards, can apply to accept any open NPP allocated scholarships. This makes a great plan B for students applying to Navy as a self-paying prepster.
Disclaimer: I'm the academic advisor for students applying to USNA and USMMA at Marion Military. In addition, I coordinate students applying for 4-year NROTC scholarships through NPP.