The correct ways to create a scatter plot are either by specifying the symbol properties when plotting (symbol, symbolPen, symbolBrush, symbolSize; see the PlotDataItem API):
pg.plot([1,2,3,4], [1,2,3,4], pen=None, symbol='o')
Or by directly creating a ScatterPlotItem, which seems to exist on my end:
>>> import pyqtgraph as pg
>>> pg.ScatterPlotItem
<class 'pyqtgraph.graphicsItems.ScatterPlotItem.ScatterPlotItem'>
See examples/ScatterPlot.py
on how to use the latter method.