They are Wi-Fi remotes. As far as I know there are no known health effects with Wi-Fi.
A few comments I found while googling: “Many bone cysts don't cause symptoms and go away on their own over time. Because bone cysts often go undetected, doctors don't know how common they are.” And “In most cases, doctors don't know why bone cysts happen. As they often occur in children and adolescents, bone cysts seem to happen as the bone grows. A solid tumor in the bone causes about 30% of aneurysmal bone cysts to form. That tumor is usually also benign.”
So I would say any link to a Wi-Fi remote and that condition is highly speculative at best. But if you want to be careful, consider laying the remote someplace and poking the buttons with your finger, or even a pencil eraser. Or, if you don’t have a Roku Stick model, you can get an IR remote.
This is kind of analogous to the idea that if you think cell phones cause brain cancer, you can limit exposure by using the speaker phone as much as possible. Even if there’s no known linkage, it usually doesn’t hurt to be cautious.