could destroy all monsters be cannon to the heisei/millenium era?

I think all of the millenium movies are stand alones besides the two Kiryu movies so it couldn't really be part of their cannon.

Just because the movie is set in 1999 does not make it canon with the Heisei or Millennium films. Destroy All Monsters is part of the Showa canon and is chronologically the last film of that series.

Besides, there isn't even a "Millennium canon." Every film, except the Kiryu Saga, is standalone and not part of any other continuity. Heck, Godzilla 2000 is (presumably) set in 1999 as is the opening of Godzilla Against Mechagodzilla, and neither of those films are connected.

Basically the timelines in Godzilla have nothing to do with the dates the movies supposedly take play essentially they're all alternate dimensions that branched out after the first Godzilla, with each series, or in the millennium's case movie, getting it's own branch.

Basically what the king of the monsters and durp said.

space station garuda has katsuo yamabe and miki saegusa, however it is non cannon to godzilla.