Shankland, 23, was with the Dons from 2014 until last year but never really made the grade in the Granite City.
Aberdeen manager Derek McInnes is delighted to have four players in the latest Scotland squad but admits it has been a source of “frustration”.
Defenders Mikey Devlin and Scott McKenna are joined by midfielders Graeme Shinnie and Gary Mackay-Steven in Alex McLeishs 23-man party.
“It shows what can be done. If youre playing well here, youre in the eye of the international manager.”
Mackay-Steven and uncapped Devlin were called up late for Scotlands 3-1 friendly defeat by Portugal last month, with the winger gaining his second cap as a substitute at Hampden.
As well as the four players in the Scotland squad to face Albania and Israel in the Nations League, Niall McGinn has again been chosen by Northern Ireland manager Michael ONeill.
“But, right across the board, we had four in the under-20s, but Frank Ross had to pull out because of injury,” McInnes said.
“We are represented at all levels, but I think more importantly at the minute is getting those players in the senior squad, which is something we have at times been frustrated by.”
McInnes was unsure whether McLeish was more open to playing players domestically than his predecessors.
However, he said: “Weve been the second best team in Scotland for the last five years and Ive always felt that, if my players and playing well and regularly, they give themselves a chance of being in the international set-up.”
McInnes thought that the “signs are very encouraging” that midfielder Lewis Ferguson, who is in Scotlands under-20 squad, would be a future full cap.
Ferguson scored the winning goal against Kilmarnock on Sunday from a free-kick and his manager said that the 19-year-old had “shown he can deliver” from set-pieces.
“Sometimes he gets bullied out the way by Niall McGinn and others to take them, but he practices them religiously in training and hes got very good technique and he fancies himself to score from that distance, especially the one he scored from on Sunday,” McInnes added.