I personally don’t know the stats for California English teachers. My colleagues are teachers. California is very competitive for teachers in good districts.
I know there may be more positions in some of the harder to reach communities in California.
You may want to check with the California Teachers Association and the California Federation of Teachers for employability.
The Bureau of Labor Statistics notes the following:
https://www.bls.gov/oes/current/oes252031.htm
Is your son bilingual? Better employability odds, I think, for California and NY.