ok, hacked-up some wordpress rest endpoints (my first php yeah!)
1. you need simpleJWT plugin to take care of auth.
2. make sure you enable jwt on all endpoints and pass &jwt=<token>
3. this is not production software! as said i am not a PHP engie (assembler, c, c++, c#, pascal but not php 🙂
4. drop the code in functions.php in your themes folder, again not correct, this is not production software, hope bm comes with official api; below is tested and works