https://www.teslafsdtracker.com puts miles to disengagement at 30 and miles to critical disengagement at 300 for all v12.x.y versions. Note: this is crowdsourced data and the users themselves get to decide what's critical and what's not.
As far as numbers required to make it fully self driving, it's at least 3 orders of magnitude worse than the big players. Waymo and Cruise routinely had 30,000+ miles per disengagement during their California testing. That's one disengagement for roughly 3 years of driving.