It's been some time coming (it was promised back in January when the game was released for Switch in Japan) but June 20th is the release date for the western release of Rolling Gunner.
Make sure you have a credit card or Nintendo Points ready because this is one game you're gonna want to play! Sometimes patience pays off! (But yes, the japanese release already has a patch with full english translation)
EDIT: A physical version is planned for later in the year.
