Over the weekend, a Ford Mustang Mach-E appeared to be successfully charging at a Tesla charging station in Franklin, Massachusetts. While Tesla charging piles aren't entirely suitable for other electric cars, Musk said Tesla will allow other electric vehicles to take advantage of their own electric vehicle charging networks.

And recently it has been found that Tesla charging stations in New England can charge the Mustang Mach-E, but this charging pile is not currently listed as an active charging point on Tesla's supercharging map.
And it should be noted that some cars can not guarantee that the charging pile can charge the vehicle by simply inserting the charging gun, because the Tesla Supercharger Station is closed to other electric vehicles, and even some Tesla vehicles that do not comply with the company's privilege requirements for the Supercharger Station. (Some recycled Tesla vehicles previously did not work on the Supercharger network.)
However, this is not the case with the Mustang Mach-E, as the LEDs located on the right side of the charging port are fully lit, indicating that the Mach-E is fully charged. According to the Mustang Mach-E owner's manual, if the Mach-E is not charged but is still plugged in, it will flash and flash red or remain solid red, indicating that the vehicle has experienced a charging error.
While Tesla has yet to open up its network of superchargers to regular electric car brands in the United States, Musk also said in July that Tesla will "open up our network of superchargers to other electric vehicles later this year." With only eighteen days left in 2021, Tesla is likely to have already started to open up its network to other vehicles, and it may be limited to newly opened supercharger stations. However, when this happens, there may also be the possibility of software errors.
In September 2020, some electric car owners in Germany were able to use Tesla charging piles incorrectly through software. Although optimizations have since been made, a pilot program for Tesla's Supercharging program was launched in the Netherlands in November. So now that this is happening in the U.S., it may not be far from Tesla to open its charging network.