I was a piker and just hit the delete button without doing any of these things. Did I lose some history that, in retrospect, I might have wanted to revisit...honestly, no! I never went back and visited my old posts and (and I'm embarrassed to admit this), none of them were likely to have any value to future generations.
Some people post great, information rich posts about how to debug .NET applications or defuse nuclear weapons. I think my greatest contribution to Reddit was making a pun that once got 54 likes.
The important thing to remember is to delete your Reddit account (and hope that AskHistorians comes to the Fediverse eventually!).
If they want to keep our data, realistically nothing we can do will stop them.
I had the same mental debate when I deleted my Facebook account years ago and realized I just don't have any power in this situation. I am deleting things mostly for my benefit; it's symbolic, like throwing away the remaining pack of cigarettes. That act by itself does nothing, but it sure doesn't hurt my chances of actually kicking the habit.
In this case, even if the data is still buried somewhere in Reddit's servers, if enough people do the same it will destroy any "value" that Reddit has left as a company. Trying to undo all of that would be a massive, likely impractical undertaking that I'm comfortable betting simply won't happen.
A part of me wants to kinda salt the earth and hopes that there will be a data shredder script that doesn't delete all comments, but instead uses ChatGPT to bloat all of them up to maximum comment length. No idea if this has a considerable effect on data size on the server. But I would be happy just imaging that it does.
A more harmless and funny approach could be to instead to just push the original comment through several iterations of translations and dialects till the original comment becomes nonsense.
The non-confrontational part might be just numb to all the corporate greed making stuff worse and is just trying to enjoy this new experience instead