root@er-x:~# cat /root/parse-set.sh
#!/bin/sh

parse_ipset() {
	local domainlist=${1%/*}
	local setlist=${1##*/}

	if [ -x /sbin/fw4 ]; then
		IFS=,
		for set in $setlist; do
			local family=$(nft -t list set inet fw4 "$set" 2>&1 | sed -nre 's#^.+ipv([46])_addr.*$#\1#p')
			echo "--nftset=$domainlist/${family:+$family#}inet#fw4#$set"
		done
		IFS=$' \t\n'
	fi
}

parse_ipset "/example.org/yahoo.com/google.com/set1,set2,set3"

root@er-x:~# nft list sets inet
table inet fw4 {
	set set1 {
		type ipv4_addr
	}
	set set2 {
		type ipv6_addr
	}
}
root@er-x:~# sh /root/parse-set.sh
--nftset=/example.org/yahoo.com/google.com/4#inet#fw4#set1
--nftset=/example.org/yahoo.com/google.com/6#inet#fw4#set2
--nftset=/example.org/yahoo.com/google.com/inet#fw4#set3
root@er-x:~#