Connman uses:

$ cat src/connman.ver 
{
        global:
                connman_*;
                g_dbus_*;
        local:
                *;
};

So indeed __vpn_ipconfig_foreach is local.

I guess wireguard.so shouldn't try to use it then and it's a bug there?

It's called explicitly in vpn/plugins/wireguard.c get_ifname, so that's not
going to work, is it?