Do you have a computer with windows vista or later?
If you do and haven’t disabled it you will have ipv6 enabled.
Therefore I think that any firewall today should have ipv6 support, or you will run a system “half open”.
This post is not about how the ipv6 support should work, refer to this post for that https://forums.comodo.com/firewall-wishlist/some-ipv6-features-and-considerations-t52055.0.html.