I run this script in scripting and this added the cffi into Blender using Python and then successfully added the Prorender plugin into Mac OS X.14.6, I hope the helps
import sys
import subprocess
import os
import platform
import bpy
def isWindows():
return os.name == 'nt'
def isMacOS():
return os.name == 'posix' and platform.system() == "Darwin"
def isLinux():
return os.name == 'posix' and platform.system() == "Linux"
def python_exec():
if isWindows():
return os.path.join(sys.prefix, 'bin', 'python.exe')
elif isMacOS():
try:
# 2.92 and older
path = bpy.app.binary_path_python
except AttributeError:
# 2.93 and later
import sys
path = sys.executable
return os.path.abspath(path)
elif isLinux():
return os.path.join(sys.prefix, 'sys.prefix/bin', 'python')
else:
print("sorry, still not implemented for ", os.name, " - ", platform.system)
def installModule(packageName):
try:
subprocess.call([python_exe, "import ", packageName])
except:
python_exe = python_exec()
# upgrade pip
subprocess.call([python_exe, "-m", "ensurepip"])
subprocess.call([python_exe, "-m", "pip", "install", "--upgrade", "pip"])
# install required packages
subprocess.call([python_exe, "-m", "pip", "install", packageName])
installModule("cffi")
