Has the Caravan layout for layers above

user_project

been published anywhere?

The physical layout? No. It's still waiting on us to finish up caravel, since it depends on all the same subcircuits. The final top-level routing for caravan is probably going to end up being done at the last minute.

Maybe a bit more specifically - should we expect these M4/M5 power straps to reach into it (as the do for “regular” Caravel) - or should we just expect the M3 power pins?

No, there are no power straps in the caravan chip. However, if you want additional current capacity, the three pads that have clamps under them (in the middle of the top row) will be stacked m3/m4/m5 on the outside of the user area, where currently there is just a m3 pin showing. The stacked metals satisfied the request of one designer of a DC/DC converter with high current capacity. I just haven't updated the wrapper layout to include the additional metal layers on the pin.