Don't want to write this by hand? GodCraft sets minecraft:dweller for you with a switch.Get GodCraftOverview
minecraft:dweller is an entity component: it goes in the components object of a custom mob, or in one of its component groups. Lets the entity belong to a village, like villagers and iron golems, so it can find homes and work spots there.
Example
Inside the components object of BP/entities/<name>.json (values are the defaults or placeholders):
BP/entities/<name>.json
{
"minecraft:dweller": {}
}