Honestly they showed no interest. When American started the route several months later I revisited it and was basically told AA would be out of the route in 6 months. Instead they have Tripled capacity and judging by the prices and loads I see the yields are fantastic. Delta is the only US airline operating the A220-100. The aircraft was designed for long haul off short runways. They could likely have also served the NY/Boston market non stop. One of the advertising points for the aircraft was it could serve the London City Airport. That’s a 4950 foot runway however only 4000 can be used for takeoff. EIS is 4650 with all of it available. Here is an Airbus comment.

Airbus provided Aircraft Analytics with caveated data specifying that, in certain conditions with certain operating assumptions in place, an A220-100 configured in a two-class configuration with 116 seats could operate sectors of up to 2,000nm from LCY

Delta’s aircraft are configured with 109 seats. That combined with the extra 650 feet of runway should easily let it serve markets up to 2000 miles with a full load. It’s also much quieter than the E175 American uses.