The short answer is yes, it would be a massive pain, if indeed it could be done at all. Shopify themes are built specifically for the Shopify platform, with the Liquid template language being used as the backbone for all Shopify themes. My recommendation would be to identify what features in your Wordpress theme you like and wish to keep if you're migrating to Shopify, and to look for themes that offer these features on the Shopify Theme Store. We provide a number of free themes developed in-house by our own themes team, but there are also a varied number of paid, third-party themes sold by approved developers that you can also consider.
I would also recommend checking out our guide on migrating to Shopify if you are doing so for the first time.
Victor | Shopify Social Care