The single topic that this question focuses on is - how to remove gingerol and only gingerol from a piece of ginger in a manner that it remains safe to eat using equipment found in a well stocked domestic kitchen.
I found Ref (1) which adds information to the question suggesting that several hours above the boiling point of water is required:
After 3 h of heat treatment at 75, 100, and 125°C, the gingerol's content was reduced by 6.8, 12.6, and 42.7%, respectively, and the shogaol's content was increased by 2.95, 4.85, and 9.34 fold, respectively. After 3 h of heat treatment at 150°C, the gingerol's content was dramatically reduced by 89.5% and the increased shogaol's content was even lower than treatment at 125°C.
(See also this article)
Below I give some examples of things that I have tried.
I am trying to find out how to make preserved ginger without pungency.I assume the main thing is to break down the gingerol into safe products. Or extract it out into a fluid that can be discarded - without removing the other tastes. Experiments suggest that boiling in lemon juice has some effect. I suspect that the acidity is the operative principle. I have tried acetic acid - eg. white wine vinegar. Success is partial. Perhaps it should be heated under pressure or for a rather long time. And research suggests sodium chloride, sodium hydroxide, or potassium hydroxide.
What is the best, most effective and most safe, way to remove the pungency?
(1) Ho, S.-C.; Su, M.-S. Optimized Heat Treatment Enhances the Anti-Inflammatory Capacity of Ginger. International Journal of Food Properties 2016, 19 (8), 1884–1898. https://doi.org/10.1080/10942912.2015.1084633.