some references put that the shape of the Greek letter pi is inspired in the lion's gate at Mycenae:
The Symbolism of the Greek Alphabet" by Thomas Taylor(1833)
"The Secret Life of Symbols" by Michael Tsarion(2004)
these references were given by Google's Bard. For me they do no like to be very scientific and trustworthy.
My question is: are there trustworthy scientific references that put some light on the subject?