You've got the start of something good here for sure. I can tell this is one of those games I'm going to go back to when I need something to chill out with.
I think there's a few things that could use some tweaking.
The "build wide" mentality doesn't work as well when I'm constantly needing to reroute pipes to build new combinations. Since pipes can only carry one color and don't automatically empty once the delivery goal was met, even building a series of machines to mix things in stages meant automatically clearing all of the pipes. I found it less tedious to just erase everything and start from scratch a few times.
This is compounded with empty pipes automatically snapping and combining with neighboring pipes. I had a few misclicks from time to time that resulted in an entire chain of pipes becoming connected, and unfortunately undoing didn't fix it (this was from the browser version, playing on firefox, in case that makes a difference!)
After I got to chapter 5 things started feeling repetitive. Especially when I was remaking colors that I had already made, delivered, and torn down to make room for a new color. And at that point every device was unlocked, so i didn't feel like I was doing anything new or interesting.
Minor things: the music got a little repetitive after a while, some variety would be nice!
A blueprint or copy/paste feature would be really useful.
Being able to mirror the mixers to have the 2- or 3- part inputs on the opposite side would be nice.
Overall I enjoyed what you've made so far. It's nice and casual and relaxing with the ability to make some satisfying assembly line chains. Keep it up!