(touch wood in advance)
I have only had a spoke problem once during a trip, back a long time ago in France, and was able to loosen my rear brake and ride with no problem with the untrue wheel until a bike store where they replaced the spoke and trued the wheel.

On my very first trip, I carried a chain whip and all kinds of stupidly heavy tools, so learned my lesson.

Since then, I have learned that the number one thing worth doing is to get your wheels spoke tensions and trueness checked and corrected by a reliable, know good wheel mechanic.
Getting the spokes tensioned properly and trued goes a huge way towards avoiding a broken spoke issue--as does not using too high pressures that will transmit a lot more impacts into the wheelset, and of course the easy one---using common sense and not bashing your bike into potholes, over curbs, whatever, when you have an extra touring load on it.

I now carry spare spokes on long trips, so if I need to go to a store, I have the right length spokes (got spares from a reliable shop where they can figure out the drive and non drive side length. My front spokes are the same length of one of the rear spokes, dont recall which.

I also finally bought one of those kevlar rope fixit kits, it cost around 20 or 25 shipped from the states and is very small and light, so stays in my repair kit. Havent used it yet, but read the instructions when I got it, so have a vague memory of how it works, but will follow instructions when I do need to use it one day.

but remember, get your wheelset checked out by a very reliable bike store, where they can use an expensive spoke tension meter and get things as good as they can and should be, this will go a long way to avoiding issues, along with being careful riding.
Totally worth spending the 25 or 40 bucks or whatever BEFORE a trip (not RIGHT before mind you) just from the aspect of not losing time and the hassle of dealing with broken spokes during a trip.

also, be sure that your wheelset is appropriate for your weight, your bike and load total weight etc, some people have problems simply because they are abusing a wheelset made for unloaded riding, or have way too much weight on a bike (rider and load) that the wheelset is overwhelmed and can keep having recurring broken spoke issues. A good mechanic should be able to tell you if you are being unrealistic with a given setup.
It would help if you can give these details to the mechanic and hopefully get an informed and honest answer if you let them know you are touring , and that the mechanic is not a young, new one with no experience of touring realities.