Shaky geriatric fingers, cretinaceous thing thinks I'm trying to move the page when I'm poking a link.
That's a very good point. Low-pass filtering the touch input would be a valuable accessibility feature. (My family have a history of Essential Tremors, so I know how big a deal this sort of thing can be.)
I saw someone's research project some years ago in which they'd written software to filter Parkinsons tremors (which apparently have a very specific frequency) out of mouse input. Sadly that idea doesn't seem to have made it to the mainstream yet. Maybe when the current generation of software developers get old?
Otherwise, have you considered using a stylus? You can get them for capacitive touchscreens. Have a blob on the end that simulates a very small finger. They're a good compromise between the frustration of finger input and faffing about driving a fondleslab with a mouse (and as a bonus, keep the screen smudge-free).
Also, on Android, there's a developer menu option you can enable called "Show touches" which draws a dot where the device thinks you're touching. It won't do anything for tremors, but I find this gives useful feedback that improves touch accuracy when tapping small features on web pages. TBH, I think it should be moved to the accessibility menu, as it's so useful.