I think, your question for dynamically restricting choices was already discussed in previous community postings.
Here is an example how it can be done with a constraint:
None alone.xlsx (12.4 KB)
Instead of the if(., …,…) also a corresponding logical and or expression would be fine.
The example does a bit more: It controls that None and Don’t know can only be used exclusively, and limits the remaining choices to maximum of 3 (incl. Other). It also controls, that if other is chosen, the user must enter some string (with at least 3 letters)