How do I "read" a variable on a while loop

You can just use

your_code | while read line;
do
    echo $line
done

if you don't mind the while loop executing in a subshell (any variables you modify won't be visible in the parent after the done).

You can write:

while IFS= read -r line
do
    echo "$line"
done <<< "$the_list"

See §3.6.7 "Here Strings" in the Bash Reference Manual.

(I've also taken the liberty of adding some double-quotes, and adding -r and IFS= to read, to avoid too much mucking around with the contents of your variables.)

If you do not use the variable for anything else, you can even do without it:

while read line ; do
    echo $line
done < <( ... code ... )