Meanwhile, the CPLP members are
"a República de Angola, a República Federativa do Brasil, a República de Cabo Verde, a República da Guiné-Bissau, a República da Guiné Equatorial, a República de Moçambique, a República Portuguesa [which is kind of cheating!!], a República Democrática de São Tomé e Príncipe e a República Democrática de Timor-Leste"
Even for Timor-Leste, one would still use the masculine article when speaking colloquially, e.g. "Onde é o Timor-Leste?"
As for what word is masculine or feminine, yeah, it's pretty arbitrary.
The China headline example actually has another wonky case: coin in portuguese (moeda) is feminine, yet "bitcoin" is masculine. Go figure!
I somehow picked up the gendering of that word somewhere despite not having set foot in Brazil for about a decade and consuming english media pretty much exclusively for the past two decades. My guess is maybe my brother mentioned it in passing. It's weird how sensitive to learning gendering of new words we portuguese speakers are.
Interestingly, the presence of articles is not actually mandatory, but adding them gives a more colloquial tone, whereas removing them provides a more formal tone, e.g. "China proibe bitcoin" reads like a news headline, whereas a person on the street might say "A China proibe o bitcoin".
I suspect this could be related to learning of word gendering, since communication with children is always colloquial, and article omission tends to only occur when there's an assumption of a minimum level of sophistication.
This observation more or less holds across the entire Portuguese vocabulary, so I think it's quite a different case from the historical analysis of the discrepancy between "american" vs "french" in english.