Hey Andrew,
Excellent write-up and awesome you took the time to share with the community
I just wanted to mention that folks should verify that their light switch does indeed have a LED and metal spring inside that makes contacts with the activation prongs, for the 'front fog light' switch DIY.
I had cracked open a US spec switch, which I bought just for the front fog light button and I notice that BMW had eliminated the polarity contacts and LED for the 'rear fog light' hack. Which I assume was some sort of cost-cutting measure, since it's not required in North America.
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So there is a possibility that some switches might not have proper connection/LED behind the dead buttons. In that case, you would just need to source the proper switch to complete this mod.