iTunes and personal compositions

I’m a music teacher.

I compose my own music (including vocals) on my Yamaha keyboard. I need to import these compositions onto my iPhone or iPad to create music videos during lessons. I use iMovie to create these videos.

I currently use iTunes to import my work but, hearing it is being closed down, I need to know how to import my own music (composed by me) onto my devices. Also, how will I get my music into iMovie?

My music will not be on streaming services as it is straight out of my head!