I requested my archive - let's see what is in there.
An alternative would be what comes out of the "Embed Tweet" function. It's a pretty sane text version of the tweet. With a bit of CSS styling, that might do. Would need some automation to pull them all. Maybe via a bookmarklet.
And then a bit of processing to create a nicely browseable html version.
Any existing solutions out there?
https://github.com/mhucka/taupe
From there you just need to write some code to re-publish them. Ideally just post them up to Mastodon?
For existing tweets, you could get an archive or pay $100/Month to extract everything through API and then cancel the subscription.
As for scraping if it's possible, I'm sure there are others on HN who can answer that better than me.