First, you can read about the "Are there different levels of Scrum Trainers in the Agile industry?"
Everyone can be a Trainer or Coach by any means. To gain trust and have a channel of continuous learning, you should be associated with a professional accreditation association.
They give you three important things -
All three are essential, especially #2, because there are not many people that can teach you at this level. People in the professional community can instead grow together with you, sharing techniques and the latest discoveries you cannot learn through other means.
If you're planning to get accredited, plan to get associated with the most professional association in the industry. That's usually 1-3 in every Agile discipline like Scrum, Kanban, and DevOps.
What you should be careful with is the alignment of the association. Don't go to the Scrum accreditation associations if you're planning to teach Kanban or go to a DevOps association if you're planning to teach Kanban. Also, it would be best if you did not go to an "I have it all" accreditation association that doesn't specialize in anything.
Let me give you some examples.
You can teach Scrum, too, if you're associated with Exin.
You can teach Kanban, too, if you're associated with Scrum Org.
You should ask: "As a professional community, what does this association stand for? What will the community members spend time learning, advancing, and being good at?"
For Scrum.org, it's their training based on the Scrum Guide. I can hardly imagine they'll know more about Kanban than the people at Kanban University. For Exin, it's their IT-Operation targeted DevOps program. It sounds difficult for these guys to know more about Scrum than the people at Scrum Inc.
In a world that's already crowded with Agile certificates, and Agile certificates are not valuable after your 1st or 2nd one, you should target the knowledge, practical skill, and ability to implement the knowledge correctly instead of collecting certificates.
You want to prove that you can contribute to the company, and mindlessly collecting certificates only contributes to your own happiness.
Once you've made up your mind, then everything becomes evident. Every professional accreditation association has some form of ascension path. Just go to their website to download it and work on it.
It takes years to be good. So, it takes dedication and belief to complete the journey.