It will be fascinating to see how this plays back in the US.
It's not uncommon for avowedly anti-union employers to have union contracts outside the US. When Walmart owned the British supermarket ASDA, for example, the GMB union was recognised. Companies seem quite adept at keeping their adaptations to local rules tightly firewalled.
But unions set the rules for the labor market as a whole, not just workplaces where the workforce had unionized.
An Amazon warehouse with zero union employees would still have to have union conditions/pay for all employees. It wouldn’t be possible to not do it. And it’s not possible as an individual employee to negotiate a contract with worse terms (the equivalent of taking work under a minimum wage level).
So in Sweden there is no recognizing unions. It’s like recognizing labor laws. Not optional.