Similar to #8755. These are settings that were added to v1.6 that need to be added to the Settings UI (or include reasoning for why not add them):

This may not be a comprehensive list. @cinnamon-msft is verifying if any are missing and will update this issue accordingly.
EDIT: verified that startupActions is the only one. Updating the issue title appropriately.

Resources:

• Documentation for adding a setting