The requirement is not actually that deep (.003") so it shouldn't impact your structural integrity much, if at all. That said, I expect the DIY suppressor maker might end up with a deeper engraving than that to have confidence that they have reached the necessary depth. Looking quickly at Quietbore's diagrams, their AL pistol caliber tubes are .065" wall thickness and their steel rifle tubes are .095" I'd imagine that most quality AL tubing you could buy will be suitable for a Form 1 build.
I wouldn't use AL on a rifle caliber can, though!