He was selected by Pittsburgh with the 58th overall pick in the 2018 NHL Entry Draft. On 15 July 2018, Hållander signed a three-year entry-level contract with the Pittsburgh Penguins.[2]
He was returned to continue his development with original club, Timrå IK, after gaining promotion to the SHL. In the 2018–19 season, Hållander scored 7 goals and 14 assists as a rookie during his first SHL season and was the second best point producer for Timrå in their qualifying games with 5 goals and 3 assists in 7 matches, in their relegation and return to the HockeyAllsvenskan.
On 29 April 2019, Hållander signed a two-year contract to remain on loan in the SHL from the Penguins with Luleå HF.[3]
As a pending restricted free agent with the Penguins, on 28 April 2023, Hållander opted to return to his original Swedish club by signing a five-year deal with Timrå IK, with the club having returned to the SHL in his absence.[8]
^McCann was expected by both Pittsburgh and Toronto to be an expansion draft casualty to the arriving Seattle Kraken; the Penguins used him to re-acquire Hållander and allow another player to be selected from their roster,[6] while the Maple Leafs (who did not have enough space for a protection slot under expansion draft rules) acquired McCann for the purpose of enticing the Kraken to select him over Alexander Kerfoot.[7]