It might surpize som, but I have used straight grained hardwood dowels from the hardware shop and can't think I ever broke one. Sometimes coal oil, and sometimes linseed /turpentine mix soak.
I Did do the bend test one time inadvertently!
I had looked long and hard at doweling in the hardware shop, selected about six, bought them and leaned them up against passenger seat in the old F 150.
Bought something else someplace, and went to put it behind the seat.
Yep, rods got crinked as seat went forward, and bust a couple.
I figured the ones that stood the bend test should be good, and they were!