As far as I can tell, the prosecution's entire case relies on an unfounded grand conspiracy argument. That by running a newspaper which supported democracy, Lai was implicitly calling on the US to impose sanctions on China.
Lai admitted to explicitly doing this - https://www.scmp.com/news/hong-kong/law-and-crime/article/32... - I believe he said he did this on multiple occasions. His arguments make no sense at all because, given his background, the only possible interpretation of that course of action would be to use sanctions to change the government.
Also, if Lai genuinely believed (as I think he must have done) that the US was going to help in any way then he was delusional. In almost every case, "freedom" fighters end up relying on the resources of hostile foreign governments to continue their activities. There is no way that the US was going to offer anything other than a publicity stunt.
Hard to address evidence that's behind the paywall of an organisation where there's concerns over editorial independence. I found an archived copy of the article you linked [0] only to find a nested link [1] for the meeting with Pence & Pompeo, which I could not find an archived copy of. As far as I can tell, the claim of admitting to lobbying could be massively overblown.
