The Fetchify Data Validation app includes the option to exclude address results for a number of regions which, although part of the UK or USA, are non-mainland islands or territories. Territory exclusions can be used alongside the Shipping Zones for your store to prevent address search results from appearing in your checkout. You can use any of the exclusion areas individually, or as many as you need as follows.

Eg. to exclude the Isle of Man and Isle of Wight from address results add the following codes in a comma separated list as follows : gbr_isle_of_man, gbr_isle_of_wight

The list below shows all the available exclusion territories