I'm also interested in getting these values and have thus far been unsuccessful.
I found this topic on a Bosch message board (https://community.bosch-sensortec.com/t5/MEMS-sensors-forum/BME688-Nicla-Sense-me-how-to-access-the-data/m-p/46408#M8368 but so far I'm getting the same results (only temperature, rest of the values 0).