You might look at analog multiplexers, there is a subset which offers
"overvoltage protection" of various forms (high-Z, hard limited, etc.).
Now any CMOS switch, not of that kind, will tend to clamp signal at
VDD+Vf and that is same as the ADC ((but more stout, if it's a
piece-part, perhaps) if you co-power it.
Surely the exact Vf and stiffness will vary. You might do a little bench
I-V testing of such candidates at your imagined threat-voltage,
threat-current levels and find one that's best for that seldom-
advertised attribute.