I'm also a native speaker of Japanese. In natural Japanese usage, "令和元年 (Reiwa gan-nen; Reiwa is the current Japanese era name)" is more common than "令和1年 (Reiwa ichi-nen)" when referring to the Japanese era name and the number of years. I think that "1年 (ichi-nen)" is used only under limited conditions, such as when only integer can be used. ...