[3][4] He attended Assumption College,[5] Armstrong was initially interested in rugby league, but turned to Australian rules football, supporting the Sydney Swans.

He was named for his AFL debut in round 13, 2009, but was quarantined along with his housemate, teammate and fellow Assumption College graduate Richard Douglas due to a swine influenza scare, and so did not take his place on the field.

[7] In September 2011, Armstrong walked out on the Adelaide Crows and requested a trade to the Sydney Swans, the club he supported as a child growing up in NSW.

The four-part show looks at "the surprising, strange, and sometimes dark history behind our most iconic stuff" – including Chiko Rolls, Speedos and Stubbies, Vegemite, Hills Hoist, the boomerang, the Victa lawn mower, One-Day cricket, and Sherrin footballs.

Guests on the program include Benjamin Law, Nazeem Hussain, Jenny Kee, Nornie Bero, Kevin Kropinyeri, Richard Glover, and Jean Kittson.

[29] Armstrong has also often appeared as a panellist on Network 10's The Project and on Fox Footy, as well as doing comedy segments on The Weekly with Charlie Pickering.

[24] In November 2023, Armstrong was one of a number of journalists who put their names to an open letter calling for greater scrutiny in the reporting of the conflict between Israel and Hamas.

[32] In 2024, a photograph of Armstrong was featured on the cover of the ABC's Annual Report, surrounded by objects presented by him in his television programs.

Glynn-McDonald is the founding CEO of Common Ground, an organisation focused on reconciliation, co-founder of First Nations Futures,[34][24] and a filmmaker herself.