The Democratic presidential candidate's campaign does not allow a large gathering because of COVID-19 restrictions, with at the most a score of people sitting at a distance.
The president appeared on Fox's Tucker Carlson Tonight for what the White House described as an on-air "medical evaluation" conducted remotely by Fox contributor doctor Marc Siegel.
Trump balked at holding the debate in that format, and Biden scheduled a town hall with ABC News for that night once Trump said he would not participate.
Polls show Biden leads heavily in key demographics including women and the elderly, prompting analysts to talk increasingly of a possible landslide victory.
Judge Carl Nichols of the US District Court for the District of Columbia late last month halted the ban after TikTok's attorneys argued that the US administration's ban infringes on rights to free speech and due process.
"China's total lack of transparency and mishandling of the coronavirus outbreak has cost hundreds of thousands of lives, millions of jobs and left untold economic destruction."
The United States first intervened in Afghanistan following the September 11, 2001 attacks and dislodged the Taliban regime, which had welcomed Al-Qaeda.
Trump was eager to return to the campaign trail, telling aides that he wanted a series of mega rallies in Republican-friendly areas in battleground states to mark his recovery.
