ISO addition for remote install

Not a perfect solution and mostly a thought experiment, it might help avoid a long trip.

Build a live persistent installation with manjaro on a USB drive
Install your preferred remote control tool and set the tool up to autostart.
Share the stick with your partner

With this stick you could in theory install manjaro on the target PC while being remotely logged in.

Not sure about and needs testing:
How you would get calamares to remain on the live USB, a normal install removes it iirc.

The stick will contain credentials if not encrypted this could be a risk of lost/stolen.