Especially for Youtube, where there are as of 2022-09 close to 6000 videos with written Cantonese subtitles Cantonese YouTube - Google Sheets
Language codes typically used:
zh-HK
zh-Hant
yue-HK
zh-Hans
yue
Cantonese has high global utility – 19th most spoken language, more than Korean, Vietnamese, or Italian. Thank you for your consideration!