It is very difficult to replace this with a pot/resistive rotation position sensor or similar.
because, in most cases, the TPS (throttle position sensor) is non-linear.
The linearity is different between about 0-10%, which corresponds to idling, and 10%-100%.
You can refer to the image search or the resistance values listed in the TPS test method in the service manual.
It is easier to find compatible ones from there.
Are there any used ones out there? It is quite possible that a similar throttle body is used in a similar year or other model.
Custom made? just one? It's going to cost you hundreds of dollars, but you want it?