One thing that my recent experience expanding our WireGuard mesh network has driven home to me is how (and why) WireGuard needs a provisioning system, especially if you're using it as a mesh networking system. In fact I think that if you use a mesh WireGuard setup at any real scale, you're going to wind up either adopting or building such a provisioning system.

In a 'VPN' WireGuard setup with a bunch of clients and one or a small number of gateway servers, adding a new client is mostly a matter of generating and giving it some critical information. However, it's possible to more or less automate this and make it relatively easy for people who want to connect to you to do this. You'll still need to update your WireGuard VPN server too, but at least you only have one of them (probably), and it may well be the host where you generate the client configuration and provide it to the client's owner.

The extra problem with adding a new client to a WireGuard mesh network is that there's many more WireGuard nodes that need to be updated (and also the new client needs a lot more information; it needs to know about all of the other nodes it's supposed to talk to). More broadly, every time you change the mesh network configuration, every node needs to update with the new information. If you add a client, remove a client, a client changes its keys for some reason (perhaps it had to be re-provisioned because the hardware died), all of these means nodes need updates (or at least the nodes that talk to the changed node). In the VPN model, only the VPN server node (and the new client) needed updates.

Our little WireGuard mesh is operating at a small scale, so we can afford to do this by hand. As you have more WireGuard nodes and more changes in nodes, you're not going to want to manually update things one by one, any more than you want to do that for other system administration work. Thus, you're going to want some sort of a provisioning system, where at a minimum you can say 'this is a new node' or 'this node has been removed' and all of your WireGuard configurations are regenerated, propagated to WireGuard nodes, trigger WireGuard configuration reloads, and so on. Some amount of this can be relatively generic in your configuration management system, but not all of it.

(Many configuration systems can propagate client-specific files to clients on changes and then trigger client side actions when the files are updated. But you have to build the per-client WireGuard configuration.)

PS: I haven't looked into systems that will do this for you, either as pure WireGuard provisioning systems or as bigger 'mesh networking using WireGuard' software, so I don't have any opinions on how you want to handle this. I don't even know if people have built and published things that are just WireGuard provisioning systems, or if everything out there is a 'mesh networking based on WireGuard' complex system.