help with creating living entity

I want to make a miner villager found in caves. My problem is to make him sell want i want him to sell, always the same not random selling and that I choose the quantities and everything. I also have this custom item I want him to sell me or that he needs for trading... How do I do? Any help would be appreciated.

Also, do you mean ground trading (1) such as piglins, or GUI trading (2) such as villagers.

1. I don't know if it is supported in MCreator. But pretty easy in coding, and only requires an Entity AI that is a based off a couple of lines.

PathNavigator::tryMoveToEntityLiving

Moves the entity. You can get a list of items;

World::getEntitiesWithinAABB

In concept, it is simple and doesn't require that much knowledge.

2. I don't think if it is supported in MCreator. And somewhat difficult in coding, more difficult than the above.