> Seller wasn’t involved in the tariffs. Rather the importer paid them

Strictly speaking it depends on the Incoterms agreed upon by the seller and buyer[1]. If the Incoterms are DDP, then the seller should pay import duties and taxes and as such is involved.

Of course sellers are typically trying to run a business, so they'll bake the taxes and import duties into the sales price. So effectively the buyer ends up paying for it, just indirectly.

This was relevant when the tariffs were introduced, as sellers with DDP goods in transit had committed to a sales price which included any tariffs and would have to swallow the extra costs when they got the bill from the freight forwarder.

[1]: https://en.wikipedia.org/wiki/Incoterms#Allocations_of_risks...

Who pays the importer?

I guess by seller parent means the US company who sold the product to the US customer not the seller who sold it to that company.