Depending on the Shopify theme, it may be difficult for users to know which variant they are currently using. Here is how to display the name of the selected variant in the default theme "Dawn".
*The theme structure is different from the Dawn version used in the post in May 2023, so the code has been replaced with the latest theme.)
Example of setting to "Show selected variant" when the variation picker is a button type in the "Dawn" theme

[How to implement] Add code to "product-variant-picker.liquid"

