> Aside from not purchasing from the listed companies, is there other action that can be taken in support, from a distance?
Support the Hong Kong Revolution, they're literately the front line when it comes to encroachment from the CCP.
If/when they succeed then the notion of 'One China' policy falls in shambles; Taiwan, Macau and possibly Tibet are all in good strategic positions to rise up and contest it as well now that China is weakened economically.
Follow up with Documentary from Daily Apple (Jimmy Lai was recently arrested for his involvement with the protests) this should be a good preface for what is happening in HK:
Also, if you speak Mandarin or have other related language skills (Turkish, Russian, Uyghur, etc), there are volunteer positions!