Regarding the "quid pro quo" in the Trump scandal, it seems that at least one US ambassador had that impression, along with a GOP senator, that the Trump administration was intentionally withholding aid (and dialoue with Trump) i to get Ukraine on the same page as them, which was to get rid of corruption and to investigate anything that might have connection to Democrats, and Biden, for political gain. And the people involved, in leading up to the Trump Ukraine call, according to the whistle-blower report was to make sure to "provided advice to the Ukrainian leadership about how to 'navigate' the request that the President had made of Mr. Zelenskyy"
One of the people in the middle of all this, Gordon Sondland, a Trump donor, who was given a government position to the EU by the Trump admin, told GOP Sen. Ron Johnson, chairman of a Senate subcommittee who oversaw the aid to Ukraine, that the aid would be held up prior to any meeting, or talks, between Trump and the Ukraine president, while seemingly contradicting what he said to William B. Taylor, Ambassador to Ukraine, when that ambassador questioned him by twitter that it was looking like some "quid pro quo", with Sondland admonishing him for even suggesting it was that and urging him not to talk about it in the open.
And, according to Kurt Volker, Special Envoy to Ukraine, Trump was obsessed in having the right people in power in Ukraine, telling him that there were "'terrible people' who 'tried to take me down'" there. Volker was often the go between the Trump admin and the Ukraine government, walking a tightrope between the two countries, while helping to set up meetings with Trump's personnel lawyer, Rudy Giuliani, with Ukraine officials. Volker cautioned Giuliani not to trust them, or put much stock in what they said. Volker claimed he was not aware that the Trump admin was trying to get the Ukraine government to investigate Biden, even though Giuliani told him that he wanted them to investigate Burusima, the company where Biden's son worked at. Volker resigned his post before giving testimony to Congress