> And for what reason to choose lua over using languages more matured on system programming like Rust..?
...you wanna talk about mature? Rust hit 1.0 in 2015 (https://blog.rust-lang.org/2015/05/15/Rust-1.0.html). Lua hit 1.0 in either 1993 or 94 (https://www.lua.org/history.html is a little fuzzy). As for reasons why Lua is suitable, and Rust is not even remotely suitable for anything core to NetBSD, the obvious one is platform support; NetBSD supports basically every platform to ever be capable of running a unix-like - https://netbsd.org/ports/ has a list. Rust supports... some of these, yes, but only a tiny fraction. Thus, Rust is wholly unsuitable (at this time) for any core component of NetBSD.
...you wanna talk about mature? Rust hit 1.0 in 2015 (https://blog.rust-lang.org/2015/05/15/Rust-1.0.html). Lua hit 1.0 in either 1993 or 94 (https://www.lua.org/history.html is a little fuzzy). As for reasons why Lua is suitable, and Rust is not even remotely suitable for anything core to NetBSD, the obvious one is platform support; NetBSD supports basically every platform to ever be capable of running a unix-like - https://netbsd.org/ports/ has a list. Rust supports... some of these, yes, but only a tiny fraction. Thus, Rust is wholly unsuitable (at this time) for any core component of NetBSD.