Then it's just a matter of biting buying the right extension cord
Right.
As TC has covered this before, consumers are clueless (and cheap) about extension cords.
Also, just because code is/has changed, doesn't address current homes and also imperfect installs. How often have I seen loose screws on outlets...
No, charging for high current, long charge time items like this should be like any other high current, long-run devices like stoves, dryers, etc, using a dedicated, properly sized circuit.
I don't want my house burning down because my neighbor was clueless and caught their lithium battery on fire.