That post does not discuss or take into consideration personal residency taxation.
Corporate taxes are taxes on your corporation and legal entity.
Personal* taxes are usually based on where you are a residency (except for American and Eritrian citizens who are taxed on a worldwide basis regardless of residency)
To open a Hong Kong company, you don’t need a physical address in Hong
Kong and your physical presence is Hong Kong is not required
While you don’t need to be present for the HK company, You are required to be present to open a bank account in Hong Kong. Also there are better options for digital nomads opening up a legal entity. See FlagTheory.com/digital-nomad
Personal taxation are taxes on flow through income to you personally, which is what this article is discussing under the context of Panamanian residency.
Regarding Panama, - yes this country is a good option for residency to lower effective personal income tax rate. You might apply under executive decree 343 which basically requires investment in real estate and a company. More details at Passports.IO/Panama
Final thought on Panamanian companies - not as good as other options as there are 3 directors required and all the documents are in spanish. However - if applying under decree 343 a company and investment in real estate is required.