Question about Creality CR-K1

there are no upgrades, because unlike other hotends and extruders, the mechanism is not accessible apart from the wire.
This is a definite advantage, a turnkey system that doesn't require any fiddling or tinkering. In short, a very well-designed system from my point of view. On the other hand, I'm a bit more circumspect when it comes to using wired systems other than the standard (abs ect). In short, I'd recommend this printer if you want a turnkey system that's quick and well designed. If you want a printer that can be configured, then you're better off with another printer :)