I own 3 944's (Turbo, Turbo S, and a 968) and have owned a 4th (another 968). There is no pulley held in place by an allen head fastener.
I guess my memory of car repairs past isn't as good as I thought. The job I'm thinking of was done 25 years ago. See if this sounds right:
I immobilized the engine by removing the starter. Pinned that off so I could remove the crank pulley bolt. (I think I only did this the first time. After that I braced a ratchet and bumped the starter???).
I recall there was a big plastic shroud under the first set of pulleys, but in front of the timing belt??? So all pulleys had to come off to get the shroud off to access the next pulleys. Sound right? My car would have been most similar to your 968. I guess it was one of those pulleys I stripped. But I distinctly remember (as does my wife, who was my girlfriend at the time (and is still today))) my agony of defeat, the tow of shame, and high cost of a stripped fastener I simply couldn't remove.
I think I stripped the bolt, then broke the pulley trying to restrain it so I could use Vise grips (which rounded the bolt further). Something like that. Those pulleys were tricky and I never had the right tools.
The allen bolt story may have come from my wife's 1986 1.8L Jetta GLI. Pretty sure the crank pulley had 4 allen head bolts. So maybe I have my stories a bit mixed up. That car had a clearance engine. I know because the timing belt broke on the highway at 110,000 miles. It too was towed but I forget whether I towed it home and replaced the belt or towed it and had it fixed. But I stripped one of those screws too.
A couple years ago I snapped a Craftsman torx bit socket pulling the seats out of a full sized Chevy club van. Must have been a T47. Did the remaining bolts with borrowed Snap On (gold ones), with no problems. Guess I hadn't learned my lesson- a lesson I'm hoping the OP and other here will learn from me: Cheap tools aren't cheap.