I know this is about post in ground, but I was in China a couple of weeks ago and looked at
wood construction which used no nails.
The wood pillars just sit on stones that hold them off the ground. Friction holds them in place and of course they have very heavy tiled roofs to increase the friction. The wooden bracket system transfers the load from the roof to the pillars.
The wood was also painted with something to prevent insects eating the wood.
This is the Piyun tower on the Ancient
City Wall of Zhaoqing built about 900 years ago. It was renovated in 1989 but I don't know to what extent.
I'm guessing the pillars held by friction wouldn't withstand the lateral forces of an earth bermed structure but can anyone make an intelligent guess? Maybe it would just need some cross bracing at the right points?
Anyway, the point is, do we really need the posts in the ground and can we not just place them on top of the ground?