The dataset from ArchiveTeam is quite extensive, and since most posts have media that are hosted on external services, it shouldn’t put too large of a storage burden on Lemmy NSFW.
For kickstarting I personally just dumped the relevant ones from my own stash (that were still up, I have a few more I’ll need to reupload because Imgur & co) and let the community take over from there, though of the 3 communities I tried it only seems to have worked for 1, so YMMV.
You could try and convince the moderators of your favorite protesting NSFW subreddits to move over here. (Reddit mirror of the list)
There was a discussion about this (specifically a reposting bot) and it’s pretty split between allow, disallow and allow only in certain subs. There are definitely a lot of communities here that are empty or nearly so, but I think most would rather see organic growth instead of automated reddit-cloning.
I have used reddit archives as one of the sources to find content to kickstart communities, but I assume you’re talking about something in bulk that’s a lot more automated.
