Ahh I see this is only useful if you setup the smartphone when in proximity to the MT wifi.
Nah ... you can perfectly set it up without mobile app.
Just did using Winbox, terminal, print QR code on screen using /ip cloud print (and make sure your terminal is zoomed out a lot using CTRL - minus)
Use QR code in Wireguard app on phone and done.
Could have done that perfectly from where ever in the world having access to that device.
Did diff check on AX3 (base setting, only using as AP with VLANs, so no firewall, nada).
2 lines were added:
/interface wireguard
add comment="cloud vpn" listen-port=54272 mtu=1420 name=freevpn-wg \
private-key="<edited>"
and
/ip cloud
set back-to-home-vpn=enabled ddns-enabled=yes update-time=no
Which is odd ... because in winbox I see the relay IP address being mentioned but it's not in export ?
Or it is once again one of those oddities with export where defaults are not shown.
Hmm ...