Maybe we could use parts from different governments to check each other. ARM CPUs are available from US-controlled sources and China-controlled sources. An Intel ARM CPU and an Allwinner ARM CPU, run in lockstep with comparators checking the bus transactions, could be useful.
Two different vendors' CPUs running in lockstep won't have their buses equal each other anyway, due to differences in implementation. Even more so, you have to have different code for a Allwinner vs an Intel ARM CPU, since they have different memory-mappings, peripherals, etc.
