I think the wheel that comes with the Savic Sky is a Rolly? I have a Rolly wheel that came with a cage and I find it quite stiff. I haven't used it as it's too noisy but I wouldn't be surprised if a hamster had trouble turning it.
I have a wooden Trixie wheel which is a very smooth and quiet wheel. My Robo can even turn the 28cm one (it's my gerbils' wheel really, I just let her use it in a playpen once) so a Russian should have no problem with the 21cm version. The wood does need sealing with Plastikote to protect it against urine. The Silent Runner is also a popular wheel. I think the smallest size is 9" but that should be fine for a Russian.
https://www.zooplus.co.uk/shop/small..._wheels/609617
https://sugarglidershop.co.uk/product/silent-runner/