>>2040790thank for the answer, but I'm sorry I don't fully get it yet.
are u saying something like: I don't need to replace anything right now, at all. I keep 1x12 -> lock/disable the derailleur by turning the screw (idk how to do it). then remove the shifter and finish?
does it make my bike more "sturdy"? I heard 12-speed chain is less durable. I just want to pedal at the 2nd smallest sprocket now for as long as I can (without paying for replacements).