If You Want to Support Hong Kong...
Hong Kong has a complex history and relationship with China that most people (including myself) don't fully understand, but that has been recently thrust into the media spotlight. When the United Kingdom handed over Hong Kong to China in 1997, it was transferred as a colony without any true autonomy, which underpins much of the civil unrest in Hong Kong today. The 2019 Hong Kong anti-extradition bill protests are examples of public sentiment boiling over due to the treatment of Hongkongers under Chinese rule.
Reports of the Hong Kong protests in Western media are certainly biased in favour of Hong Kong; most news outlets support the protesters' demands of democratic freedom, and rightfully decry the use of police violence against protesters. This is the case simply because we are able to strongly empathize with the situation in Hong Kong. Just like how most of us would be vehemently against the subversion of democratic law, Hongkongers who have had a taste of freedom and democracy under UK rule are not willing to give up their rights and identity. However, from a mainland Chinese perspective, the protests don't make any sense. Why would a city want to destroy itself and be so unproductive? Is Hong Kong another example of Western values creating failure? Why bring shame by not working towards a unified China?
I am fairly certain that China will not acknowledge the demands of the Hong Kong protesters because: a) this would set precedent for other countries/states attempting to leave China, and b) this would show weakness in the Chinese Communist Party and generate conflict among its citizens. Most of the cohesion among Chinese citizens is due to the benefits reaped from China's extreme economic growth, and the just as extreme crackdown on dissent and freedom of speech. The CCP wants its citizens to march forward unified under the promise of global economic power, ignoring the lack of rights and freedoms. Deviation from this path might result in unrest.
Personally, I feel that it is cruel and unethical of China to strip Hongkongers of their values and freedoms, because China is essentially destroying their identities. What the CCP is doing to Hong Kong has similarities with the cultural genocide happening to Uyghur Muslims in other regions in China, that is, strictly enforcing the CCP's sacred values onto minority groups. Unfortunately, there isn't much I can do to alleviate this situation. Even if I sign petitions and contact my local representative, these actions might not generate a large impact due to the reasons I described. If you want to support Hong Kong and its protesters, the best action that you can take is boycott China and its products. The economic growth that is propping up China also happens to be its biggest weakness, and through this you can hope to send a clear message to the CCP.
Addendum:
I would like to stress that I appreciate the amazing things that the CCP has done, bringing hundreds of millions of Chinese citizens out of poverty, and contributing greatly to our global trade and economy. My mother country, South Korea, also went through a similar economic transformation that incorporated aspects of government-influenced capitalism and authoritarianism. However, in the 1970s, even under economic growth, many South Koreans protested the lack of democratic freedoms and rights which ultimately led to a new democratic constitution in 1980. My hope is that one day, China will be able to do the same.