Using the artwork would be fine. We make them available under the Creative Commons at https://github.com/ros-infrastructure/artwork/tree/master/distributions
However, I’d suggest that you consider a variant of the 9 dots theme with a Ukrainian flair. For example the Japanese user group has a red dot in the middle: About the ROS Japan Users Group category
And many of our github orgs have graphics too. There are some examples here: https://github.com/ros-infrastructure/artwork/tree/master/orgunits
It provides a nice simple way to make it your own but keep a simple consistent theme.