If they created their own root instead of partnering with another CA, which is what I assume you meant, then they would need a lot of time (2 yrs just to be inc

If they created their own root instead of partnering with another CA, which is what I assume you meant, then they would need a lot of time (2 yrs just to be included in apple+msft+mozilla) and the process would be public. An intermediary created by a partner would solve the problem but would require a partnership.