It would be nice if:

• sp-sim accepted configuration for the initial contents of the various cabooses that it reports. This would allow you to tell it to emulate a gimlet-e or whatever so that we could use real artifacts to update it. (RIght now, you can't use, say, faux-mgs to update a simulated SP with an artifact from a CI-generated TUF repo because the board won't match because the board is SimGimletSp.) [sp-sim] configurable initial contents of the cabooses #8734
• during a simulated update (for SP, RoT, RoT bootloader, etc.), sp-sim cracked open the binary it's given, reads the caboose, and then reports it back after the next simulated reset. In other words: more faithfully reflect what real SPs do in terms of what's reported for the cabooses after an update + reset.

These will probably be necessary to be able to test a lot of the code for automated update of SP/RoT. Right now we have unit-style tests that use fake images but they just do one fire-and-forget update. The automated system will need to use feedback about the current state to know if the update has already happened, etc.