This can all be done with GitHub repositories and signed commits. The workflow would be every "transaction" becomes a pull request that requires approval from several owners of the repository and the CI pipeline only passes and merges the PR to the main branch if the commits are signed by some minimum number of approved contributors.
There are also things like joint bank accounts that require approving transactions so this is all already possible with existing technology, all without having to put up with gas fees or any other blockchain nonsense.