Here's what the command does:

1. docker run -it alpine /bin/ash -c ... Get clean alpine image, call its shell (interactively) to execute a script
2. apk update && apk add curl nodejs npm ... install the prerequisites
3. curl -fsSL https://nostr-svrn.codeberg.page/install.sh - your install script
4. | sed 's/set -e/set -ex/' | sh - edit the set -e line to make it echo back so we can debug