Why do you need that if there is no char limit and you can fit the entire thread in a single note?
Does any client offer a "thread view" like Twitter? By which I mean displaying a sequence of tweets from the same author in a straight line that is easy to read, instead of treating everything as normal replies?
#[0] what do you think of adding this to https://github.com/mikedilger/gossip? I can try to implement it in a couple of years if you don't do it before me.
Discussion
Twitter's big superpower was that it made people write short meaningful notes. A thread is a collection of short meaningful notes, not a giant piece of filler text splitted into many pieces (although some people do these, it is horrible).