If you're looking for an alternative to ContinYou, HereAfter is a good choice. The app lets you record and share stories and memories with family members, using a conversational interface to make it more personal. It has interactive recording, guided prompts and secure authorized access so you can leave a legacy of personal stories and photos.
Another alternative worth checking out is My-Legacy, which is geared for estate planning with generative AI. The service helps people through the often confusing process of creating legal documents like medical proxies and wills. It doesn't have future messaging, but it does protect data privacy and present information in a clear, understandable way, so it could be useful for people who want to get their affairs in order and ensure their families are better prepared for what's to come.