This is not really a bug.
ctypes uses 'objdump', which is not available by default.
(There are reasons not to install binutil on Solaris)

There is no 'objdump' but Solaris has 'elfdump', instead.

ctypes.util.py can use 'elfdump' instead of 'objdump'.

#        cmd = "objdump -p -j .dynamic 2>/dev/null " + f
        cmd = "elfdump -d 2>/dev/null " + f

#        res = re.search(r'\sSONAME\s+([^\s]+)', os.popen(cmd).read())
        res = re.search(r'\sSONAME\s+([^\s]+)\s+([^\s]+)', os.popen(cmd).read())        if not res:
            return None
        return res.group(2) # <<<--- 

//

./Modules/_ctypes/libffi/config.guess
also uses objdump so that file probably needs to be updated as well.

Thank you for your attention.