Is the Cantonese spoken in Guangzhou standardized, and if it is, is it different from Hong Kong and Macau's standard Cantonese? Do some characters have different standard readings in each region, much like how some characters have different standard Mandarin readings in Mainland China and Taiwan? The closest example I could find for Cantonese is the character 「米」 when meaning metre. Below is the explanation given on the Yue Chinese Wikipedia:
If Cantonese in Guangzhou is indeed standardized, is there an authoritative source that decides on the standard reading of characters? I have found dictionaries published in Mainland China like 廣州話正音字典 and 廣州話方言詞典, but I don't have much insight on how close those dictionaries are to standardized Cantonese in Guangzhou, assuming that exists.