Ford has a patent for something very similar. It would be a semi truck that could tow an EV behind it and recharge it via regen braking.
Ford has filed a patent application that proposes charging electric vehicles by flat-towing them behind another vehicle.
www.motorauthority.com
But I doubt this method will actually become real. It does not seem very practical.
I think a better approach would be to have robotic chargers that could plug in for you. 5 years ago, Tesla teased a prototype robotic charger that could automatically plug in your car. The idea was going to be that FSD would be able to automatically pull into a spot and the robotic charger would take care of the charging. When charging was complete, the robotic charger would pull out and FSD would continue the trip. This way, the FSD Tesla could do an entire trip with no human intervention, not even for charging. Obviously, that never happened.