The relations would be set during front-end editing, using a searchable selectbox which allows several to be saved in the column and also adding/removing them later. New input type needed..?
See attachment for simple html table mock-up showing the idea.
For example the relation between products AH52 and XA22 could be set during editing either one of those products, no need to do the procedure separately for both.
The links should open the master detail pages for the products in question, so possibly also depends on https://features.wpdatatables.com/108 .
This kind of functionality would be extremely useful later on in my project, it would be very nice to see it implemented in the future.
Most likely in my use case the “Compatible with” data would need to be visible on master detail pages only, the column should actually be hidden in the table view.