I would probably consider `dispatch_command`, `fire_and_forget_command`, or `send_command`, depending on what the typical use-case is intended, and what self-documenting fits. 

`spi_thing.command(Comm)` is open to interpretation.
`give_command` feels more of a "change of ownership without intent"
`instruct` feel a bit too "intimate" if you will. spi implies some sort of dissosciation/seperation/discance between start/end points. When I think "instruct", there's this kind of expectation that the path of communication is extremely _direct_, with feels at odds with there being an spi bus between the send/receive ends.