Which kind of wall switch? How they are connected?
It will not work. Or if, then tell me,it would be interesting for me too. For me I have a solution like this: I take two Sonoff T1, one I connect with power and the lamp. The second I connect only with power. Then I make 4 szenes in the EWELink-app.
if (1) on then (2) on, if (2) on then (1) on, if (1) off then (2) off and if (2) off then (1) off. The result: One switch changes the light and the other switch, the second switch changes only the first switch (and with this the light).
A time ago I saw a modified Basic in ebay with a possibility to connect a normal switch, but was not for me.
I hope I described it good, if not, please feel free to ask.