Might be a little late for you, but you can also do this by converting the image in GIMP and exporting as PBM binary. The PBM format is monochrome, and aside from the header lines (can readline 3x to skip these) is the correct format to load into a framebuffer object.
with open('my_image.pbm', 'rb') as f:
f.readline() # Magic number
f.readline() # Creator comment
f.readline() # Dimensions
data = bytearray(f.read())
fbuf = framebuf.FrameBuffer(data, 128, 64, framebuf.MONO_HLSB)
To display just blit it to the display's framebuffer (note you need to invert, since ON pixels are dark on a normal screen, light on OLED).
display.blit(fbuf, 0, 0)
I wrote up some the conversion options in more detail here:https://www.replrebl.com/article/displa ... -displays/
if you need them. But "GIMP -> Set dimensions -> Index 1bit image -> Export pbm -> Binary" should get you there