This resembles the spark ignition device on some gas kitchen ranges and ovens. Not all demand water heaters have this electrical device. You should check with the manufacturer for models that have this feature. Most tankless models have a life expectancy of more than 20 years. In contrast, storage tank water heaters last 10 to 15 years.
Most tankless models have easily replaceable parts that can extend their life by many years more.
This list does not cover all available sources of information on tankless water heaters, nor is the mention of any publication, product, service, or organization to be considered a recommendation or endorsement. 6-9, April 1988. Extended Range Tankless Water Heater, J. Harris, Harmony Thermal Co., 1993. 55-56, November 1988. 51-54, January 1997.