I have an EcoNet Bulldog servo actuator (z-wave enabled) that sits over the ball valve that is my main water shut off in the crawl space (read: difficult as hell location to get to in an emergency). I can put leak sensors in the drip pan for my water heater (already have one), behind the fridge where the ice maker connects, under the sinks, under the dishwasher, and maybe under the clothes washer as it discharges into the laundry tub (I already have a plug for the washer that stops it if the tub gets too full, so this would be more like for a line blowing out or the machine itself leaking).
[NOT A SPONSOR, I paid for my unit out of pocket] https://www.amazon.com/gp/product/B07DJZCFBH This ships in from Canada, and you'll get an email from them asking about your valve and setup before it ships so that you get the right one, both in regards to connectivity, and the valve size you're working with, from 1/2" up to 1-1/2". Connectivity is either WiFi or ZWave, or even relay-contacted for older or manual systems. You have to pick one of those 3, but there is a clutch mechanism and a handle on the top to crank over the valve in an emergency. It takes 12VDC, 700ma during cycling, 60ma standby, so it can be run from an SLA or lithium pack during power outages. The control box that has the antenna on it (if you go that route) has the receiver, the 12V input, and a cycle button to "manually" operate the valve and pair it to the system. That box connects to the valve actuator assembly via a 6pin mini-din connector (AKA a PS/2 port from back in the day), which can be extended (M-to-F) about 50' (I got conflicting information from the rep, but I'm only going 25' into the crawl space, so should be fine).