This is very possible and practical, in fact I have been doing it for a few years with OpenWB and my own 10.5 kWp PV generator.
This is based on a current sensor where the mains enter my house. OpenWB tries to increase or decrease the EV charging current so no current is coming into the house or going out of the house.
So when I switch on the coffee machine, within a second or so OpenWB will decease the current to the car so I don’t have to buy energy.
In that image you can see that until 12:08 we have intermittent sun / pv production (green line) and most of the time very erratic power usage in the house (black line). The system is wildly adjusting the car charging speed (blue line) to keep me from buying or selling electrical power (red line).
Once set up this works really well and I rarely use non-PV power to charge my car - even in deepest winter I guess 50 % of car charging is done by solar.
Here in Germany people now start getting dynamic pricing where the cost of electricity changes every 15 minutes - mostly it’s cheap when the wind blows and the sun shines. Wallboxes like OpenWB can use that pricing to decide when to charge your car. Others use just Solar radiation to automatically decide when to charge.
This is all technology available out of the box right now.