I have a Python project (a game) I would like to sell eventually. Would it be considered, by Python standards, acceptable to use a .pyc file instead of a regular .py source file to distribute the game, for security reasons? Would this even be effective? Or, on the other hand, is that just not what .pyc files are for?
Is is 'alright? Yes, the license allows you to distribute .pyc files.
Is is 'effective'?  It will most likely be unnecessary, as there will be no commercial reason to copy your work.  If it is super good, people will de-compile or write similar games in another language.  See jonrsharpe's link.
Is is intended?  The main purpose of .pyc files is to avoid unnecessarily re-compiling Python code by caching the result.
Is it proper to use .pyc files?