IPv6 + IPv4 dual stack with reverse-proxy to LXC containers

Hello,

I have several lxc containers with web applications on proxmox.
Container with apache passes 80/443 requests to containers and with ipv4 everything is ok.

Now, I would like to implement ipv6 for the containers while keeping ipv4.
I was able to set up GUAs for the containers (without NAT - directly to the VM), but I’m facing the problem, that I have to set up web server in each container to be able to access the web apps via ipv6. And moreover I have to manage both reverse proxy and all the web servers inside containers.

How can I implement ipv6 without the need of installing web server in each container and need of maintaining a lot of web servers?
I read that ULAs + NAT66 is a bad thing to do.
I asked that question on different forums and was told that HAProxy can help to solve that problem.

Could you please give me an idea on how such scheme would look like if I use haproxy?
Are there best practices for such situations?

Thank you very much for any suggestions in advance.