Default variation price.

We are building a webstore with roughly about 10000 different products with one attribute (item condition). The attribute has two terms (New / Used).

We have set the New item condition variation as the default and the variation stock is following the “main” products stock (Manage stock? unselected). The Used variation has its own stock amount and price (Manage stock? selected).
My question is, if there is a way to batch update the default variations (New) of multiple products at?the same time like when the product type is set to simple instead of variable product?

So far we can batch update the stock quantity of the default variation using the rest endpoint “/wp-json/wc/v3/products/batch” but if we understood correctly the price can only be updated using the “/wp-json/wc/v3/products/<product_id>/variations/batch” endpoint. Or maybe there is a way to have the default variations price follow the “main” products price similar to the stock? Also can the price of the default variation somehow be left empty if it is possible to follow the “main” products price since now it is required for the variation to be displayed.

Our prices are constantly fluctuating so having a way to batch update multiple products at the same time would be nice instead of having to have a call for each product individually.