I may have already mentioned this so apoolgies if I have (I have memory issues myself due to cerebellar Ataxia!) but a weighted belt I got from the US helped me a few years back and I noticed recently somewhere an ad for weighted vests for dogs.
Found it.. https://xdogvest.com/
They advertise it for building muscle and fitness but with Ataxia the tremor is because your brain is struggling to work out where its limbs are in space (proprioception) and when you add weight it helps the brain achieve this so it can help reduce the tremor and help the brain co-ordinate the body better. I've never tried this theory on a dog as my Inca has since passed away a couple of years ago before, but for her the cart worked the same and helped keep her body more steady, but she did have bad hips too. If a dog ONLY has Ataxia no other physical complications that may require it to need a cart then a weighted vest may help it walk better and reduce tremor.