Courses/resources you can recommend to start with ML/AI

I am a backend dev and would like to learn a little about ML/AI. No concrete plan to use the knowledge on any project, but think it will become more and more important in the next years and want to be prepared to that.

What resources can you recommend to get started?

Should be self-paced or with max 2h mandatory sync time commitment per week and if possible be less than 100$ per month

I am more interested in fundamentals and concepts than a project driven “code along this python project” kinda style.

Thanks for your help!