They aren't solenoids, they are actually motorized. The orange boxes on top of each valve is a motor housing. They take a little bit of time to open or close, about 5 seconds in either direction. A DN15 is as close to 1/2 NPT as you can get, just need to use some teflon tape.
I bought them on eBay from some manufacturer in china. I know pandemic stuff has made that sorta taboo, but whatever. I use 24VDC, and that variety is a little more expensive but only by a few bucks. The 220VAC variety is a little cheaper, but I wanted to keep all control power the same. Roughly $30 per valve.
They told me the valves are potable water safe, so that's good enough for me. They are made of a brass housing with a stainless ball inside. They're only rated for ~200 degrees F, so it works for almost all parts of brewing. I just need to let my IC run a little bit during cool down before opening up the valves. I believe this is because the ball sits on a plastic seat, I imagine the plastic could warp if it gets too hot. Luckily, when full closed, it doesn't look like water touches the plastic. The plastic seat looks "contained" until medium flows through when open. If it becomes a problem, I can take the motors off the top of the valves and find a way to install them on fully stainless valve bodies instead.
I am using a Siemens PLC to control all of my process, so I can open or close any/all of them at will. I set up a program where you select which "mode" of brewing you want to do (heat, move strike, vorlauf, etc), and then all appropriate valves open or close to create that route. Then my graphical interface will display that route only, and allow for pump or heat control as long as it won't run dry.