Travelled on it, its rostered as a 3 car, its hardly busy and the timings don't justify providing any food. 7:00 and 17:05 are the busiest
The trolley can handle the vast majority of needs, the classic 20% of items but they are the 80% most frequently purchased.
I've gone 15+ years since I last ate a meal on a train in Ireland, used the trolley a fair bit.
The only routes where catering does well is where there is first class Dublin Cork and Dublin Belfast because there is volume and business
As far as I have been able to determine, there are more services per week serving breakfast now than anytime in the last 10 years. Massively more services will a trolley as well.