@domubpkm about Russia - it's all OK... you can install anything you want... even you can sell your phone on an internet noticeboard, to private hands. But official business can only sell something that complies with the law - smartphone must have a number of components installed, all sorts of Russian search engines and office applications, etc...

When no networking applications are running... only one TCP connection I can see to the 188.166.168.0/21 DigitalOcean (hosting provider) US IP pool, port 5001/TCP, from service process, /usr/lib/ubuntu-push-client/ubuntu-push-client
Android / Vendor stuff is in the LXC sandbox, and as I can see, these processes have access to the network:

root@ubuntu-phablet:~# lxc-info -n android
Name:           android
State:          RUNNING
PID:            1416
IP:             10.15.19.82
IP:             {my LAN WiFi IP here}

@lakotaubp Are you sure that this problem is specific to this phone model?

@prog-amateur said in Is our phone phoning home to Google?:

@markatrafik , do you know what purpose is ubuntu push client ?

Is it a server related to push for SMS for instance ?

Perhaps, as in Android, apps maintainers can use this feature to report through the Cloud about changes in settings (for example: a new list of maps or remote servers), rather than when everyone is connecting to their Cloud and wasting battery of the phone.

Another question, do you know what is the 10.15.19.82 address ? > I have tried to reach it in a browser to find the owner without success.

Perhaps it is some kind of IP network for internal use, as I understand it, the external network may not be available, for example not given to DHCP for some reason, but communication within the phone is needed, within the same OS communication can be organized through localhost or named sockets, and here between different OSs.

I hope that people knowledgeable in the subject will correct me, I am purely out of general knowledge...

@stanwood Yes...
Of course! I even made sysmlinks in /usr/local/bin as some people advised, included the user in several groups, e.g. dialout, all dependencies, adb and fastboot work, I flashed TWRP with this fastboot - fine, tried it from root as well, in short, provided it with everything ubports-installer needed, tried also the version that works via snapd according to these instructions:
https://snapcraft.io/install/ubports-installer/debian
and the ubuntu version with cross-installation of all the necessary packages:
ubports-installer_0.8.7-beta_linux_amd64.deb
The result is the same for all of them - a brick.

P.S. The installer finds the phone, identifies it as Lavender, does something fun with it... It downloads a lot of files it needs, flashes it, sends it to reboot and - bricked. I wait 15 minutes and nothing loads, maybe I should have waited a hour, it do somthing?
But it seems to me that every minute the "watchdog" was triggered and the phone rebooted, but I can't say for sure.