At this time I believe that Anonymous can help support the Hong Kong protests through:
collection of evidence of how the state is misrepresenting and/framing protestors and/or the protest movement so as to support it's legitimacy and to support the DEMAND for the labeling of the protest as an act of riot to be retracted. (Ie. There have been footage showing police planting weapons on protestors as they are being arrested, videos showing police personating protestors and conducting crimes that are then framed on protestors, recent videos have shown ready built barricades along with bricks, tables and even gas containers believed to be set up so as to frame protestors.). While footage has been attained, there is no evidence to indicate that the police or state had directed these actions to be taken, such incriminating information would help to give credibility to these already widely circulated rumors.
collection of evidence that shows how the state is involved with censorship and coverup of their own crimes. As mentioned by the previous post by Dang State, it is suspected that casualties and fatalities directly resulting from police brutality are being covered up. Such evidence would help support the DEMAND that an independent commission of inquiry must be implemented to address police brutality.
collection of evidence or disclosure of information that the current leaders and political figures of Hong Kong actions or inactions are being directed by the state. This will reinforce and prove that they are indeed puppets of Beijing this supporting the DEMAND that genuine universal suffrage just be implemented so as to ensure Hong Kong's continued autonomy.
collection of evidence to show that arrested protestors are being framed, mistreated, not being given fair trial, and if possible evidence of state involvement in these actions so as to support the DEMAND that arrested protestors be granted full amnesty.
A last but not least, that evidence be collected disclosing state surveillance, censorship, and propaganda that is meant to mislead the public eye and international audience. Many stated backed media, persons of power and various individuals are suspected to be deployed by the state to discredit protestors and their cause. This has lead to widespread polarization among the people of Hong Kong and even those abroad. Hate crimes are already occurring in democratic nations where those in support of the protests are being targeted, receiving death threats and many fear retribution upon their families. An LGBTQ group in Montreal was also kept from participating in the pride parade as the organizer had allegedly received threats. Cyberbullying is rampant, hate crimes have increased, trolls are everywhere. The reliability of media, press and journalism is questionable now as many are believed to be controlled by the state.
These are just some ideas of how anonymous may be able to help shed light, justice and hope to those in Hong Kong in their fight for democracy, human rights and freedom.