What are some ways for a non-Chinese person to learn Mandarin without enrolling in an expensive program or course, preferably through online resources?

you can search free course in youtube, first, you have to understand how pronounce in chinese, it’s very important, and you can watch video to understand how are Chinese characters formed in history, and finally, you can download “Cici” app (ciciai.com),it’s an chatbot can talk with u in Chinese and english, you can practice your pronounce and grama with AI. it’s useful.