Can CSS variables be watched, (need a smart cookie)

The best thing since sliced bread and absolutely the most revolutionary thing I have seen in my time as Dev, is CSS variables, it's shocking because it's something that should have been there from day one.

Let's get to the question, given I can get and set CSS variables in JavaScript , can I also watch for changes to the CSS values on the fly?

Other than polling, are there any ways to observe a live CSS variable change?

onCustomPropertyChange

I think the answer is no.