Lua has a significant strike against it in being 1-based when everything embedded you'd want to put Lua on is 0-based.
In addition, the point of having Javascript is so that I can get my junior software folks (proxy for any inexperienced programmer) to write things for my embedded hardware instead of having to haul out my senior staff engineers who have 20 years of experience writing C for embedded devices.
Look at Arduino vs. Raspberry Pi/BeagleBone. Arduino has way more developers because it was orders of magnitude easier to program. Ecosystem is important.
In addition, the point of having Javascript is so that I can get my junior software folks (proxy for any inexperienced programmer) to write things for my embedded hardware instead of having to haul out my senior staff engineers who have 20 years of experience writing C for embedded devices.
Look at Arduino vs. Raspberry Pi/BeagleBone. Arduino has way more developers because it was orders of magnitude easier to program. Ecosystem is important.