Unfortunately this can now be called "Vietnam International Defense Expo 2021" - the exhibition was confirmed to have been postponed to an undetermined date next year. Covid-19 has also disrupted a number of other planned Vietnamese-hosted events such as the ASEAN naval exercise that would of been conducted off Nha Trang.
Previously, Vietnam International Defense Expo 2020 will take place from October 25th-27th at Gia Lam airport in Hanoi. Not only will this be a chance for Vietnam to promote the new weaponry & equipment it has manufactured,it is also expected to feature aircraft flight demos - the first of their kind at any Vietnamese defense expo. Since a large variety of foreign companies are expected to be showcasing their wares we could maybe see foreign air forces such as those of the US, Russia, or Singapore demonstrating their assets.
This expo is occurring around the same time as the ADMM+ meeting. Therefore, the defense ministers/secretaries of Brunei, Cambodia, Indonesia, Laos, Malaysia, Myanmar, Philippines, Singapore, Thailand, Australia, China, India, Japan, New Zealand, Russia, South Korea, the United States, & other foreign delegations are expected to attend.