The Washington Post reports:
Days after the two presidents spoke, Trump’s personal lawyer, Rudolph W. Giuliani, met with an aide to the Ukrainian president in Madrid and spelled out two specific cases he believed Ukraine should pursue. One was a probe of a Ukrainian gas tycoon who had Biden’s son Hunter on his board. Another was an allegation that Democrats colluded with Ukraine to release information on former Trump campaign chairman Paul Manafort during the 2016 election.
“Your country owes it to us and to your country to find out what really happened,” Giuliani said he told the Ukrainian president’s aide, Andriy Yermak, during the Madrid meeting. Yermak, according to Giuliani, indicated that the Ukrainians were open to pursuing the investigations. The aide reiterated the Ukrainians’ plea for a meeting with Trump, a summit that would be an important signal to Russia of Washington’s support for Ukraine.
According to the above-linked article, the Ukrainians believed an in-person summit with Trump would send a signal of US support for them to Russia. Trump refused.