[coldtea]

Them is fine.

It's short for "Have them [Node bozos improved it], though?"

Or, equally likely it, refers to deno and bun ("deno and bun has really made Node focus and improve", "Have them (deno and bun) really made Node focus and improve, though?")

[joshuacc]

Your expanded version is also incorrect.

[coldtea]

It's a common idiom used in slang and "urban" dialects for decades...

(Also the expansion was meant as a joke in case it went woooosh - I don't mind-read to know what the OP meant)

[jfengel]

That is nonstandard English, at best. It's found in some uncommon dialects.

Without the expansion I don't know of any native English speaker who would say it.