1/ It uses Fly.io[0], which can automatically pause your database after all connections are released (and start it again when new connections join).
2/ It uses Oriole[1], a Postgres extension with experimental support for S3 / Decoupled Storage[2].
3/ It uses Tigris[3], Globally Distributed S3-Compatible Object Storage. Oriole will automatically backup the data to Tigris using background workers.
I wouldn't recommend using this in production, but I think it's in a good spot to provoke some discussion and ideas. You can get it running on your own machine with the steps provided - connecting to a remote Tigris bucket (can also be an AWS S3 bucket).
[0] https://fly.io
[2] Oriole Experiemental s3: https://www.orioledb.com/docs/usage/decoupled-storage
[3] Tigris: https://www.tigrisdata.com/