With a suggestion from @kring I was finally able to solve this using mapproxy to serve a WMS service for my custom xyz pattern/scheme urls, and use it with the CesiumWebMapServiceRasterOverlay. Closing the feature request!
With a suggestion from @kring I was finally able to solve this using mapproxy to serve a WMS service for my custom xyz pattern/scheme urls, and use it with the CesiumWebMapServiceRasterOverlay. Closing the feature request!