Hi!
There is LXC and there is LXD. The commands that you show are for LXD, which is easier and better to use. The command to manage LXD is lxc which probably leads to some confusion.
To get your container to use a public IP address, you need to either set up a bridge on your host’s network interface, or use macvlan.
In both cases you can get the DHCP server of the LAN to give automatically an IP address. Or, if you wish, you can set up static IP addresses.
The issue with a VPS provider like OVH is that you should arrange earlier to get more than one public IP addresses. By default, you get a single public IP address. Therefore, do you have additional IP addresses from OVH?
(I am changing the category for this post from LXC to LXD).