Simple fan condition monitoring could be done with IIS2DH accelerometer. We have also simplified reference design available in very small form factor. Please see below link for schematics, layout and BOM, this board is not available for ordering though.
For HW&SW development and testing itself STWIN is recommended, hosting the same IIS2DH. For more accurate monitoring of fans with FFT, IIS3DWB is the recommended sensor. https://www.st.com/content/st_com/en/products/evaluation-tools/solution-evaluation-tools/sensor-solution-eval-boards/stdes-fanpre01.html#overview
