Yes, Hyvä is compatible with Magento 2 Open Source from 2.4. version upwards. The Hyvä Theme is the frontend theme developed natively for Magento 2, designed to help merchants streamline their complex and multi-faceted eCommerce operations while driving both sales and customer loyalty. 

A single theme installation integrates seamlessly with Magento 2 Open Source, giving merchants access to various useful features designed to optimize efficiency and increase profits.