If you are a FiraCode fan, you probably want to use its beautiful Symbols in coding as well. This can be done with Fira Code Symbol Minor Mode.
Fira Code Symbols can help your code more readable.
install Fira Code Symbol font made by @siegebell
additionally, you can install prettify-greek from Melpa for greek symbols
Fira Code Symbol Minor Mode will automatically enable it with no further configuration
(require 'fira-code-symbol)
put fira-code-symbol.el
into your load-path & add the above code in your init.el file
M-x fira-code-symbol-mode
enable / disable Fira Code Symbol Minor Mode in current buffer
(add-hook 'python-mode-hook 'fira-code-symbol-hook)
enable Fira Code Symbol Minor Mode mode in python major mode automatically
M-x enable-fira-code-symbol-in-major-mode
enable Fira Code Symbol Minor Mode in all buffers opened in current major mode & add hook to the current major mode's hook
M-x disable-fira-code-symbol-in-major-mode
disable Fira Code Symbol Minor Mode in all buffers opened in current major mode & remove hook from the current major mode's hook
You should know that this function will remove fira-code-symbol-hook from prog-mode-hook
(if it has) as a side effect
(global-fira-code-symbol-mode 1)
enable Fira Code Symbol Minor Mode globally, It's probably not a good idea to have Fira Code Symbol in a major mode like org-mode.