The values of slider1 and slider2 are synced via the kernel.
With illusionist we make this static so it runs without a kernel.
import ipywidgets as widgets
sliders1 = widgets.IntSlider(description='Slider 1')
slider2 = widgets.IntSlider(description='Slider 2')
l = widgets.link((sliders1, 'value'), (slider2, 'value'))
display(sliders1, slider2)