As mentioned by Drix in a previous comment, our LED strips will have the effect of a Faraday cage. As the selected WiFi module communicates with 2.4GHz-waves, the corresponding wavelength is about 125 millimeters. Way to big to cross a stitch of approximately 1 centimeter. We would like to avoid this but we don’t really have the choice. We have to put the WiFi antenna outside the sphere. Otherwise, no wireless communications allowed.
Hopefully, a Faraday cage only blocks electric fields (and electromagnetic waves as a consequence). Hence, magnetostatic fields are perfectly measurable inside the sphere. The strips does not put any restrictions on the IMU. In the opposite case, it would have been tough.