Start by naming any country that France borders. Then name any country that borders any of those countries. Then keep going until there are no more countries left to name.
Got everything except Madeira, but I might have also missed Lusophone if I didn't mistakenly try to type in Lusaka. However I remember Lusitania being the ancient Roman name for Portugal as it was also the name of the Portuguese-colonized planet in Speaker for the Dead.
You misspelled one word in that question "Which modern-day mainland African countries where colonized by the Portuguese?" Should be were instead of where.
You should include Angola as a correct answer.