At the moment, it is a grey area of the new Canon. Unless, or until a guideline is established by LFL, it can be assumed to be potentially Canon.
While anything from Legends can be "canonised" (by including it in a newcanon novel or reference book or video game) - I'd say that FFG isn't in the "canonisation business" - Wookieepedians seem to agree - it currently places FFG stuff under the Legends banner.
So - until, say, the Scurrg, or the MC30c, or the Assault Frigate Mark 2 appear elsewhere, their appearance in Armada doesn't mean anything for "canonverse designs" - at least at the moment.
Still fun to see them though.