The only experience I have with the harnesses you link is the NetAudio. I used their harness on my install and it was very high quality with zero issues.
Here is where some future planning and additional information is needed. Your profile says you have a 2021. Is your truck a “Classic” or a 5th gen? Mine is a 2018 so a classic would be quite similar but a true 5th gen may be different.
The easiest way to differentiate is how many lug nuts do you have on your truck wheels? Five lugs you have a Classic and six you have a 5th generation. If you have a Classic I can link here to the wiring T-harness I used from NetAudio.
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netaudio.com
It’s an $83 harness but is the very basic of what you’ll need and it may be worthwhile to invest a little more now to facilitate future upgrades. The basic harness I linked simply isolates the eight wires for the speakers, left, right, front and rear for use with a four channel amp like the Kicker Key. Since you intend to install subs at some point it may be best to add a LOC (line output converter) now to the harness to make that addition easier at a later date. I do not have subs nor do I intend to add them so the basic harness worked for me. You can still use the basic harness and add in a LOC to run the subs in the future just in case you wind up not doing that upgrade or you may choose to use a high level speaker input to power a sub amp and never need a LOC.
As far as the Key amp is concerned please note. It does not need resistors to power the speakers nor does it need a LOC to tap inputs. I ignored NetAudio’s recommendation of resistors on the advice of Kicker tech support that the Key amp has line resistance built in using the high level speaker inputs. In other words you don’t need RCA jack connections to add the Key amp. You simply run the speaker outputs from the T-harness directly to the Key amp wiring harness and it does the rest. The Key amp will show the factory radio speaker resistance without additional line resistors. You also do not need a trigger wire to turn the Key amp on. It has a built in internal sensor that powers it up as soon as you turn on the radio.
You may read online that using high level speaker inputs causes noise on the output side and that without a dedicated trigger wire you’ll get “pops” when the amp shuts off but I can honestly tell you that I experienced none of those scenarios with my Key amp. It’s one of the reasons I love that little amp, it does just about everything well and without the need for additional equipment or cost. It’s a unicorn that does just about everything without added complication and it also has a built in DSP (digital signal processor). Is it a thousand dollar amp? No, but for a couple hundred bucks you get a nice upgrade without much headache.
One last note to this already lengthy reply is the Key amp is “bi-ampable”. What that means is you can use one single speaker channel input to the amp and it will give you four channels of output. This comes in handy with the six speaker Ram audio systems as the front doors and dash speakers are wired as one. In other words your left dash and door speakers are wired together and your right dash and door speakers are wired together. If you use the Key amp in bi-amp mode you can power both door and both dash speakers individually with one speaker wire from the factory radio. You can then use the remaining three sets of speaker outputs from the factory radio to power the rear door speakers and add a LOC for subs to the oddball channel. If you go the bi-amp route you will need to run new wiring to at least the dash speakers which is pretty easy.
