import bpy

def sheepit_set_compute_device(device_type, device_family, device_id):
    # either CUDA, GPU, CUDA_0
    # or     NONE, CPU, CPU

    bpy.context.scene.cycles.device = device_family
    bpy.context.preferences.addons['cycles'].preferences.compute_device_type = device_type
    
    devices = bpy.context.preferences.addons['cycles'].preferences.devices # 0 => cuda, 1 => opencl
    for device in devices:
        device.use = device.type == device_type and device.id == device_id

sheepit_set_compute_device("CUDA", "GPU", "CUDA_NVIDIA GeForce RTX 2080 Ti_0000:01:00")