The Hong Kong government is not much different. Their actual language policy is "Chinese and English are the official languages of Hong Kong. Committed to openness and accountability, the Government produces important documents in both English and Chinese. Correspondence with individual members of the public is always in the language appropriate to the recipients. Simultaneous interpretation in English / Cantonese / Putonghua is made available to meetings of the Legislative Council and Government boards and committees as needed." https://www.csb.gov.hk/english/aboutus/org/scsd/1470.html
So they recognize Cantonese and Putonghua as different spoken forms, but only one written language. I've never seen a Hong Kong government website offer translation into both Cantonese and Mandarin, it's always just Standard Written Chinese with a choice of Traditional or Simplified characters.
Most written Cantonese content on the internet is probably produced by Hong Kongers in informal contexts such as forums, but then it's not clearly marked as such and might be mixed with Standard Written Chinese and English.
I think the largest collection of monolingual Cantonese text is probably Cantonese Wikipedia (which is small) and the largest collections of translated Cantonese I'm aware of are even smaller: Tatoeba with 6095 sentences https://tatoeba.org/eng/sentences/show_all_in/yue/und and CantoDict with 1547 sentences http://www.cantonese.sheik.co.uk/scripts/examplelist.htm
But there might be larger datasets I'm not aware of, which is why I was asking.