Hello, Cozdred.
We appreciate your thoughtful request and support. The senior team has concluded these coins have sufficient representation in several existing competitive sets, including the sets under the multiple "Multiple Countries" category, below. You may create a Custom NGC Registry set, if you wish.
Gold Sovereign, One Per Ruler Per Mint, 1817-Date, Circulation Issue
https://www.ngccoin.com/registry/competitive/multiple-countries/multiple-countries/5998/
https://www.ngccoin.com/registry/competitive/multiple-countries/multiple-countries/5999/
https://www.ngccoin.com/registry/competitive/multiple-countries/multiple-countries/6000/
Also, we have a backlog of requests for new slots and sets for coins (and notes) that currently have no representation in any existing competitive NGC (or PMG) Registry sets. We are focusing our limited resources there right now. Thank you.