I am hoping to early-access the game in beta before Christmas. However, I need to include charted songs for people to play.

You can see some gameplay videos here: https://notesfrommagic.com/index.php/18-pmvs-i-ve-made-with-notes-from-magic

Just having any kinds of songs is not enough - they have to be "charted", as in, made compatible with Rock Band or Guitar Hero.

If you have made or know pony-related charts for Guitar Hero or Rock Band with all difficulties and vocals charted and have permission from the song author for the song to be included in NFM, please contact me via Discord at https://discord.gg/XfStfXf

Alternatively, you can also contact me through the forum.