I've used these magnetic heaters before to pre-warm the oil and the block;
Although they obviously won't "stick" to an alloy block - the oil pan would most likely be steel.
I too would advise against running dry.
Curious about the mineral oil - I've never used it for break-in. If you can find some Shell Rotella (Truck) oil - it has copious quantities of ZDDP Zinc. If not I use just a standard 10w-30 motor oil with a couple of bottles of STP oil treatment in it. STP also has ZDDP. I run the first batch of oil long enough to break in the lifters, then dump it along with the filter - This gets rid of a lot of the assembly lube too. Another batch of oil with ZDDP to break in the rings - no more than 50-75 miles is required. Then dump and install Mobil-1 Synthetic for the long haul. Once the rings and lifters are seated, the engine is just slowly wearing out rather than wearing in..