Google is telling me that the mesh for a Faraday cage that would block WiFi could have hole sizes up to about 5 mm. Suppose you made your faraday cage (or at least the part that goes in front of the screen) out of 40 gauge wire (0.07874 mm diameter) with the wires spaced 2.25 mm apart.
On a 70" 4K TV a pixel is about 0.4 mm x 0.4 mm. If the mesh were close to the screen I think about 30% of the pixels would have wire in front of them. Of those 30%, 1/6 would both a horizontal and a vertical wire in front (let's not go crazy and talk about orienting the mesh diagonally or anything like that), and 5/6 would only have one wire in front of them. So that's 70% of pixels not interfered with, 25% having one wire in front of them, and 5% having two wires.
The 25% with one wire crossing would have about 20% of the pixel occluded by the wire. The 5% with two wires crossing them would have about 36% occluded.
My guess is that the screen could be seen pretty well through that.
On a 70" 4K TV a pixel is about 0.4 mm x 0.4 mm. If the mesh were close to the screen I think about 30% of the pixels would have wire in front of them. Of those 30%, 1/6 would both a horizontal and a vertical wire in front (let's not go crazy and talk about orienting the mesh diagonally or anything like that), and 5/6 would only have one wire in front of them. So that's 70% of pixels not interfered with, 25% having one wire in front of them, and 5% having two wires.
The 25% with one wire crossing would have about 20% of the pixel occluded by the wire. The 5% with two wires crossing them would have about 36% occluded.
My guess is that the screen could be seen pretty well through that.