Head coach Dan Campbell has called this a "redshirt year" for Detroit Lions rookie quarterback Hendon Hooker, which is expected as he works his way back from a torn ACL. Hooker seems likely to start the season on the PUP or NFI list.
More recently, Campbell said a timeframe to have to activate Hooker is not on the radar yet, while also praising the work the rookie signal caller is putting in.
It feels likely Hooker will be on the Lions' 53-man roster at some point this season, it's just a matter of when. The NFL rule allowing a third quarterback to dress but not count against the list of active players in a game opens that door a little more, however slightly. It will primarily come down to his health, even if he's just the "emergency" third quarterback.
Hendon Hooker will be activated by the Detroit Lions at some point this season
On Monday, Dave Birkett of the Detroit Free Press (subscription required) offered an extra layer to when, or if, Hooker might be activated this season.
"Players who start the regular season on NFI must sit out at least the first four games,” “If a player spends the entire season on NFI, the team has the option of tolling his contract.“"
"That could be especially appealing to the Lions with Hooker as a way to obtain an extra year of control on a rookie quarterback who is a long shot to be a meaningful contributor this fall. But a Lions source familiar with the thought process on Hooker said that is not in the Lions’ plans, and emphasized Hooker is expected to join the roster once healthy.”"Dave Birkett
The Lions have the option to keep Hooker on the NFI list (Non-Football Injury, since his injury happened in college) all season, and thus they'd be able to toll his contract to gain an extra year of control when he's unlikely to meaningfully contribute this year. They won't do it though, according to Birkett, in a good faith move as much as anything.
We also shouldn't forget Hooker is already an older rookie, at 25 years old. Consciously pushing his team control past the current four years of his rookie contract would be a weird move right now.
It's still unlikely he sees the field as a rookie, since it would (at minimum) take significant injuries to Jared Goff and Teddy Bridgewater. But Hooker could/should be seen in uniform before the season is over, which will be cool even if he never plays.