For France, there is data available at https://www.rte-france.com/eco2mix. (RTE is the public service in charge of maintaining the electricity network.)
Looking at the data a bit, it is interesting that the carbon cost per watt is not correlated with the current energy consumption. "When is power the greenest" has fairly different answers from "when is power demand the lowest".
For Germany, there's PeakPick (https://www.peakpick.de/webapp/index.php) which follows the same idea. There's also Energy Charts (https://energy-charts.info/index.html?l=en&c=DE) which has lots of interesting graphs regarding energy data. Seems like Energy Charts also contains data for other countries.
Nice, have you consider using a "tesla wall" to recharge it at low picks and use it for normal consumption? I guess it could be tested with that webpage data what the average saving would be
In particular (in French):
Looking at the data a bit, it is interesting that the carbon cost per watt is not correlated with the current energy consumption. "When is power the greenest" has fairly different answers from "when is power demand the lowest".