Is there a way to export ALL translations into a single .PO file? To translate my website, I need to export translations one by one per group type.

This gets to be confusing as some fields share core terms ect...

Is there a way to do a consolidated ONE .po file for all translations?
Each entry in .po file has only two strings;

msgid untranslated-string
msgstr translated-string


Thus, by it's very nature it can only keep two languages: original and one translation. So no, there is no way to do it because format does not support that. For details, see documentation.