Hyvä Themes
Trial
Hyvä Themes is a sane alternative for headless/PWA solutions, using the PHP-templating system that is built into Magento.
Hyvä clearly demonstrates the flexibility of Magento by implementing a completely new frontend framework that "just works". The code is easy to understand and follow, the frontend is extremely fast compared to the traditional Luma-based themes, and it scores quite high in the Google PageSpeed ranking.