From Ender IO 1.12.2 Wiki:

The Conduit Probe has 2 modes:
In probe mode you can right-click an Energy Conduit to display details about its network, an Item Conduit to run a simulation of transporting the item in the other hand, or a Redstone Conduit to display information on its connections, including Redstone Level sent/received.
In copy/paste mode you can shift-right-click to copy a conduit connection's settings and right-click to paste them.
Use Shift-Mouse Wheel or 'Y' to change mode.

Copy/paste should be the priority as I believe it's the most important function of the conduit probe. Energy and Redstone network details are likely straight-forward too but Item simulations may be tough to do and I'm unsure if there's a great deal of want for it. (Please comment if you used the Item Simulation regularly and would like it to return).

Tagged as a 1.21 feature request, but should likely be backported to 1.20.1 where possible.

if I implement this in 1.20.1 will it be accepted?
I don't have enough experience with 1.21