yeah, to get the nut off. I was thinking you were suggesting a method for the title " how to get the flywheel off without the puller". Something was lost in translation....
Yes, a strap wrench will work for removing the nut but so will a simple flywheel holding tool... you can go buy a 1" wide piece of flat stock from the hardware store. Cut one strip about 8" long and drill a hole big enough that a 8mm bolt will fit through it. Take the balance of the length (they usually sell it in 3" pieces so the other 28" dill a hole at one end and then about 8" up from that end drill another hole. Put a bolt in each of the end holes and then bolt the two strips together loosely. The bolts at the end make a "spanner wrench" to fit down into the flywheel. Total cost is about $8