Depending on what your threat profile is, if you are being targeted by nation-state actors, you do not have the best chance of coming out the other side unscathed. I don't think that switching from MS to various open source infrastructure is going to help you, especially when you consider the fairly reasonable reality that most advanced state actors probably have multiple zero days in various software projects stored in case they need to use them.
"The reason we haven't been hacked is because we still run 16‐bit POS systems, and today's hackers don't know how to fix anything is such a small address space."
