As we are all aware playing with electricity profesionally or for pleasure can be hazardous and even fatal. For me the 'safe' approach is to objectively understand the risks and to act in mitigation of those risks. Unfortunately, risk mitigation is more of a subjective activity which is why the topic always seems to cause much debate with sometimes conflicting views.
With regard to isolation transformers I find the following article helpful from a hobbyist's perspective. Others may or may not find the same.
https://sound-au.com/articles/iso-xfmr.htm
Alan