Both .pyc and .py files are mostly found as Python scripts so perhaps some way to convert one to another is possible using Python development environments. You should probably consult various Python related support forums or some other collaborative platform, such as Stack Overflow.
Convert Compiled Python script source code to Python script language source code.
We have found one software suitable in our database for this conversion.
Microsoft Windows software - convert pyc to py on Windows
One of the prominent programming and scripting languages
Convert from pyc file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.