The Fandom Post is reporting that Shout! Factory has added the English dub of the Maquia: When The Promised Flower Blooms anime film for streaming on Amazon. The film has no purchase options and it is only available for streaming for Prime members.
The story of Maquia: When The Promised Flower Blooms is described as:
The people of Iorph have a lifespan of hundreds of years and maintain their teenage appearances for life, but when the peace of this town is shattered by those who want the secret to their longevity for themselves, a young girl named Maquia is forced to escape. Wandering the land alone, upon finding an orphaned baby she chooses to raise him, but as this boy grows up so the difference in their lifespans is thrown into ever-sharper relief.
Source: The Fandom Post