PPP along with QAT and STP are federalist Sindhi ‘nationalist’ parties who work within framework of Pakistan and contest elections. They favour more autonomy.
While Jeay Sindh factions are separatists and adhere to ideology of Ghulam Murtaza Syed who also happened to be founding father of Pakistan. They don’t contest in elections as they consider Pakistan illegitimate due to which we can’t know their exact support base because it decreases and increases every time.
You can see the amount of people present in ‘Freedom rally’ of JSQM at Karachi on 23 March 2012 (literally Pakistan day).