While PayPal is now available to Ukrainian citizens, the Sketchfab Store is utilizing a particular PayPal product and API integration called PayPal for Marketplaces, which is not supported in every country. Unfortunately, Ukraine remains unsupported for this integration.
Our Store team will continue to monitor the situation, as well as PayPal product offerings, and welcome Ukraine-based sellers on the Sketchfab Store as soon as they are available.