How to generically catch channel triggers?

In Rules DSL? No, you cannot group Channels/Channel triggers, etc. You have to list them all individually.

There is some advanced stuff you can do in other languages to trigger on any event that occurs on the event bus and then filter down to just those you care about, but that is not generally supported and requires digging down into the raw openHAB JSR223 APIs.

But for an example in a UI rule, see Thing Status Reporting [4.0.0.0;4.9.9.9] which uses a generic trigger to listen for all Thing status change events to trigger the rule. Again, stuff like that is no possible in Rules DSL.

You cannot link Event Channels to Items directly. So you’d have to write rules to convert the event to an Item update which is even worse than the problem you are trying to avoid.

That won’t work for a couple reasons. In addition to the fact that you can’t link an event channel to an Item in the first place, there is no such thing as a triggered rule trigger for Items.