Mosquito probably is the closest to what you want, but you are correct that it doesn’t have current sense. Valentine took all his designs down some years ago, but there’s an alternate version here to see the components MosquiNo - Yukon concept
The STM32G031 is a little slow for SimpleFOC, though it would probably be fine for the low RPM of a robot arm. G431 is luxury, but the smallest package is 5x5mm instead of 4x4, and a little more expensive.
For the driver, MAX22213 is excellent for small size with current sense, but LCSC doesn’t carry it so you’ll probably have to do the assembly yourself. I use it on my stepstick. And if you’re assembling it yourself, then there’s a better chance you’ll be able to fit a CAN transceiver since you can do full double-sided rather than just the encoder on the back.
Step/dir can be problematic with long wire runs due to the possibility of electrical noise causing false steps, which never get corrected since it’s a purely relative protocol. I2C could work for sending absolute positions without taking up any board space, though it is of course more vulnerable to noise than CAN. But probably fine for a mini-arm.