Hi boardarch,
That's a very nice target ! Unfortunately I do not know of any consumer grade accelerometer which can achieve this kind of accuracy, especially over a wide temperature range. The BNO055 has built-in calibration which can typically keep the pitch and roll error <2 degrees.
This is an order of magnitude higher than your requirement. With good mechanical design and smart calibration routine (not automatic like the BNO055), <0.5 degrees can be achieved at room temperature, but would require periodic manual recalibration.
https://community.bosch-sensortec.com/t5/Knowledge-base/BMA4xy-accelerometer-series-design-guide/ta-...o_o
