Yes indeed, but would be easier if the hs_command_template was present.
In this particular case, the device is expecting hue/saturation values in JSON:
{ "h": xxx, "s": xxx }
Following your hint, now using RGB options:
- rgb_value_template: template converts HSV to RGB
- rgb_command_template: template converts RGB to HSV
How to make conversions using Jinja2? Check out this topic: Using HSV / HSB to set colored lights
Pretty long templates, but they do their job
In my case, minified the code into a single line.