To measure current/ power is not part of STWIN but STWIN has many expansion connectors with STM32 ADC capability, see especially schematics of STWIN in databrief document. Components recommended were as example TSC213 and TSC2011 using high side shunt and TSZ124 operational amplifier high low side shunt. You could have look on this page https://www.st.com/en/amplifiers-and-comparators/current-sensing.html and example development kits for the analog signal portion here: https://www.st.com/content/st_com/en/products/evaluation-tools/product-evaluation-tools/amplifier-and-comparator-eval-boards/steval-aetkt1v2.html.
