There is no way to guess how your boat was wired up. Pretty much every boat, even production boats, are custom done.
You may have a boat where things were done the simple way: The 110 outlets on the boat are only powered by a 110 shore power
connection, which is made manually. The boat is new-ish, there will be at least ground fault protection near the point where power comes into the boat, and there should be AC dual breaker(s) as well.
If you invest in one of the books
electricity, there are options for isolation transformers and other equipment
as well, there's no telling what is on your boat.
The next more common and expensive option is to have an inverter on the boat, which makes 110VAC from the boat's own 12VDC power. In some cases that is MANUALLY turned on when it is wanted. In other cases, there's an automatic transfer switch and the inverter turns on whenever the shore power
is disconnected. And either way, there are some inverters that can actually sense when a 110 device has been plugged into a socket--and then they fully power up the inverter to supply 100 only when it is needed.
Plenty of options, plenty of things past owners might have done right or wrong. You really need to crawl around, pencil and pad in hand, and take some notes about what you have and how it is connected.
As for Alexa? Any of those systems only control devices that have software
drivers written for that system. So all you can control, are devices made to work with Alexa. Unless you're using generic devices (like relays and switches) that allow you to hook up any load to them. And these days, there are a lot of devices where "just" throwing the power on or off won't turn the device on or off. You'll have to explore specific equipment to find out your options.
Having heard my friend's "Alexa" speak up with inane questions when no one asked it anything...I wouldn't trust one with anything important. They've been proven to do almost anything (including sending out audio to random parties) without any real reason. Great concept
, but like many Amazon and Google
products..."In need of adult supervision".