Are there any use cases/documentation about how litestream can be used within a docker based deployment? (Eg where systemctl wouldn't be used)

Here's their docs on running in a Docker container: https://litestream.io/guides/docker/

You'd probably want to put the sqlite db in a volume & run litestream in a separate container that restarts automatically on failure.

Systemctl's only in there to restart it if it crashes; litestream itself is (iirc) a single cli binary.

This is documented on the Litestream website.