Pretty much, the exact timeline is:
2019: Dessalines (and maybe Nutmoic? Not sure when he joined) start making lemmy
June 2020: R/CTH banned
June 2020: they scramble onto lifeboat discord
July 2020: devs make chapo.chat using the lemmy code as an actual replacement for r/cth, at this point federation is not a thing in lemmy yet
~August-November2020: the chapo.chat devs officially fork the code (to add things like emotes, improve performance for their much larger site than lemmy.ml at the time, etc.)
~November 2020: lemmy main code now has federation, chapo.chat’s code is too far removed to remerge, can’t use the federation code
March 2021: chapo.chat renamed into hexbear.net
December 2021: it’s announced that the devs cannot maintain the current fork, and they need to get back upstream to the rest of lemmy code
June 2023: Hexbear gets back close to the rest of lemmy code, still maintains a slight fork, especially for the UI
August 2023: the Hexbears are unleashed