According to what Arpon Basu of The Athletic reports on The Athletic Support podcast, teams looking to acquire Pierre-Luc Dubois will have to rely on the trade that sent Jacob Trouba to New York.
In January 2019, the Jets traded Trouba to the New York Rangers in return for Neal Pionk and a first round pick, which will ultimately be 20th overall in 2019, Ville Heinola.
So if the Habs want to acquire Dubois right now, they'll have to pay some kind of Justin Barron or Kaiden Guhle, plus the Panthers' first pick, next season.