You can copy compilable Kotlin definitions, which I’ve created with the help of an old ts2kt tool for my KVision framework (https://github.com/rjaros/kvision/blob/master/kvision-modules/kvision-chart/src/main/kotlin/pl/treksoft/kvision/chart/js/Chart.kt). The sources are published with MIT licence.
Of course you can also use KVision to easily create charts based on chart.js 