For your team to truly succeed in becoming self-organised, the product owner(s) needs to be on board as well. The processes and structures need to be in place to serve the team with what they need.
This means that sometimes you will need to coach the whole organisation, including stakeholders and managers. If you’re not provided what the team needs in specs, time, data and necessary resources, your chances of success is greatly hampered.
I find where organisations often fail is a flaccid attitudes to requirements. “We’re agile, we don’t need to be rigid about requirements.”
This leads to a number of problems, frustrations and delays in development because no one knows what’s been decided, who decided it and who to ask should questions arise. There needs to be agreement on a process to produce and document requirements in a structured way. How that looks can vary, but there needs to be an agreed upon formula for it. You may call it Scrum, Scrumish, Kanbanesque…