Hi. Thank you for the mod. Can you please invent something to read the contents of the chest? Like allow attaching wire to it?
I also tried https://mods.factorio.com/mod/Inventory%20Sensor mod - it doesn't work either (not that it's intended to).

Glad to hear you find this mod useful.

Unfortunately, unlike the wooden chests, steel chests are using Prototype/Container that contains several wire connection properties; linked chests are using Prototype/LinkedContainer that is completing lacking this part.
In fact, I was also surprised to find out the game devs decided to do it like that, when I was creating this mod and tried to update my train station circuit. (Since I love to use circuits to check stockpiles quantity at the stations.)
The most feasible approach will be to request the devs to add wire connection support to Prototype/LinkedContainer (like this request.) Then it will be trivial for me to follow suit (or actually no changed needed).

Factorio 1.1.62 has finally added the ability to add circuit network connections to linked chests. You do have to add them though, as the default prototype does not have them currently. (They also added the ability to use filters on the chest slots too.)