Universal adapter of 2 expansion cards

I have an idea to make a device which allows to create an adapter from 2 expansion cards and the device itself as
expansion card<–>device<–>expansion card
Since I currently know absolutely nothing about expansion cards, can someone tell me if it is realistic and if not where the problem is???

This is an interesting but deeply flawed concept.

Generally, a connection interfaces require one “host” and at least one “client” (also called master/slave). This is called asymmetric communication. This is not a universal rule, but it applies to all of the connections implemented in Framework expansion cards (USB, HDMI, DP, SD, and even the Ethernet card in the sense that the network interface expects a network on one side and a computer on the other). Adapters must support this, and generally only support one direction of communication.

In the case of a Framework expansion card, the “host” is the Framework laptop. Thus, the USB-C end connects to the host device (pretend that the Ethernet expansion card doesn’t exist for a moment). Remember this.

Now back to the “universal adapter”. Let’s just call the central piece the “universal adapter”. The expansion cards would have to plug into the universal adapter by USB-C. I know this because, if not, the remaining exposed ports would not be useful.

Here’s an example for the HDMI and DP expansion cards:

<-HDMI-> expansioncard <-USBC-> universaladapter <-USBC-> expansioncard <-DP->

Recall that the USB-C end is the host end. Thus, the universal adapter is the host of both connections. Do you see the problem? Neither the HDMI nor DP port goes to the host. That means you can’t plug this into a computer, so it’s not useful. The expansion cards are not designed to communicate in the direction that you want them to.

You’ll have the same problem for any* combination of expansion cards.

Putting aside the fact that almost all combinations of expansion cards make no sense. SD to HDMI? Sanity check failed.

*Yes, I did gloss over the Ethernet expansion card. In theory, you could create a device that uses it (you could create half of an HDMI over Ethernet system, I suppose) but in that case there is no reason to use the Ethernet expansion card–just integrate an Ethernet connector.