Tax free options in Spain

An older post https://www.tripadvisor.com/ShowTopic-g187497-i44-k12930776-How_to_avail_Tax_Refund_Non_EU_customer_from_Apple_store-Barcelona_Catalonia.html

I've seen places offering tax-free purchases but it is usually at a pretty high minimum purchase (several hundred US$). Your cheap USB adapter likely won't qualify unless it is gold plated with platinum components. ;-)

I don't think its quite as simple as saying you're a non citizen visitor --> https://taxation-customs.ec.europa.eu/guide-vat-refund-visitors-eu_en

Whether you want to jump through so many hoops for such an inexpensive purchase is up to you, however.