It's too late to do anything about it now but I wonder if it would've been more effective if all the participating subs agreed on a common time (i.e. 12:00AM UTC or whatever) to go dark rather than leave it up to each subreddit.
Also, while I don't think it's nearly as comprehensive as the GDPR, I believe people who live in California can do something similar under the California Consumer Privacy Act.
Do those tools rely in any way on pushshift in order to work? If so, I don't know if they'll work now since Reddit cut off pushshift.io's access to the API back in early May.
I don't think that's likely to happen. Based on the AMA announcement, I'm guessing that - at most - there will be a few (temporary) concessions made to moderators and some (empty) promises to work on accessibility.