Convertible car seat for car seat challenge?

Has anybody been allowed to do the car seat challenge with a convertible car seat instead of an infant car seat?

My daughter was born Tuesday just barely preterm (36w4d) but of course they still have to do all the premie assessments (not complaining, very grateful for the diligence).

Anyway, we never bought an infant car seat because we don’t own a car so buying a car seat that would only be used a handful of times while traveling before she’d outgrow it didn’t make sense. Instead we just bought a highly rated convertible car seat.

It is rated down to 5lbs and she’s 5lb 8oz so she does fit in the recommended weight range. I’m just worried they won’t accept a convertible car seat for the car seat challenge. Because I was worried about the challenge and that she might be under 5lbs, we borrowed a friend’s infant car seat to bring to the hospital. Turns out it’s expired so we can’t use that one (and wouldn’t want to!)

If my SO has to go just buy a new infant seat new tomorrow it’s not the end of the world, but would obviously we would rather not spend the money if we don’t have to.