I wouldn't say "supported". Language support generally includes:

- display/rendering
- input
- keyboard layouts
- fonts

Only few years before even PCs supported all of these and it will take more years to get this in all gadgets. So, the only expectation now is to at least display the characters well. Input is the next priority which can be solved by 3rd party apps for time being once the display issue is solved.

- spellcheckers
- dictionaries

We don't have reliable and exhaustive solutions for these yet even in PC. Only some online dictionaries and alpha level spell checkers for browsers are available in FOSS.

Ravi