I have completed translating endsets.sh into endsets_nft.sh using the native sets capability in nft. Tested working on Debian 11.

The files are located here:
endsets
https://raw.githubusercontent.com/endwall2/endsets/master/endsets.sh

http://nguipxnkrp3qrzrlduhsatpcpwehnblzmlkc5ifiumxq4z5jlh4lwvid.onion/endware/endsets.sh

endsets_nft
https://raw.githubusercontent.com/endwall2/endsets/master/endsets_nft.sh

http://nguipxnkrp3qrzrlduhsatpcpwehnblzmlkc5ifiumxq4z5jlh4lwvid.onion/endware/endsets_nft.sh

Let me know if the files are working for you.

I also made some minor bug fixes to the following files:
endwall.sh, endwall_nft.sh, endlists.sh, endlists_nft.sh, endsets.sh, endsets_nft.sh. Located in the usual places.