Paid and FOSS are mutually exclusive. Open source and FOSS aren’t.
But how, you ask? Free means having the right to do whatever you want with your copy including make copies and redistribute. Thus, how can it be free while demanding a payment before allowing usage?
That’s why I said, FOSS Droid? Nah! Open Source Droid? Knock yourself out. I’m actually looking forward to supporting some of the developers of apps I love.