None of these guys would be particularly bad options, but if you pick up anyone that isn't on an expiring contract, you probably handcuff yourself for the expansion draft.
Looking at everyone there though, I'd assume that McDonagh wouldn't waive, Florida likely wouldn't move Nuti, given that they just acquired him, as
@nhl_oilers said, Zadonov likely costs the same as what Chicago paid to get him (Saad), and even though Colorado has a replacement for him, and will likely lose Graves (Or Toews) in the expansion draft, I can't see them moving a piece like him without getting a decent NHL piece+pick back (Which seems unlikely). They're a contender, and are likely happy to keep him.
I'd say that McNabb, McCabe or Oleksiak are the only realistic targets here, and likely wouldn't cost much (McCabe is, IMO, the more valuable player of the 3).