Just don't bother. At the scale you're working at, if something tries to run and, e.g. The user doesn't exist, just throw an exception, email the team for a man

Just don't bother. At the scale you're working at, if something tries to run and, e.g. The user doesn't exist, just throw an exception, email the team for a manual fix. If(if!) it becomes too common, throw in a retry or two. You have better things to be doing in a startup vs distributed transactions (and honestly, microservices...)