The bq cervantes[1] is open source[2] but isn't so cheap.

[1]: https://www.bq.com/es/cervantes-3-bq [2]: https://github.com/bq/cervantes

I'm planning on picking one up soon (or, hopefully, a Cervantes 4 if it comes out...). I'm (fortunately in a position where I can be) willing to pay the extra to support F/OSS out of the box :).