In short it seems to allow one to save data to your personal machine, while using web applications.

Here is a video about the project ( though somewhat old)

https://remotestorage.io/
https://community.remotestorage.io/
Hosting https://wiki.remotestorage.io/Servers
Docker: https://github.com/libresh/compose-remotestorage

Current apps: https://wiki.remotestorage.io/Apps
I find Sharesome interesting

From website:

Traditional Web Apps

No-Backend Web Apps

Unhosted Web Apps

Own your data

Everything in one place – your place. Use a storage account with a provider you trust, or set up your own storage server. Move house whenever you want. It's your data.

Stay in sync

remoteStorage-enabled apps automatically sync your data across all of your devices, from desktop to tablet to smartphone, and maybe even your TV.
Compatibility & choice

Use the same data across different apps. Create a to-do list in one app, and track the time on your tasks in another one. Say goodbye to app-specific data silos.
Go offline

Most remoteStorage-enabled apps come with first-class offline support. Use your apps offline on the go, and automatically sync when you're back online.