In my opinion, boiling water is pointless.
RO makes more sense, it works without power. If you lose water pressure, you would have lost it if you had a propane burner too so the solution would be water storage, if you’re storing potable water, you don’t need to boil it.
Now if your goal is to have a burner for cooking, that’s a different story.
Just remembered I also loved this one for Wok cooking. Would definitely boil water.
When I was blowing glass by melting it in a pot inside an insulating dome, when I started with 1 20# tank, I could produce ice on the outside halfway up on humid days at 70F. I added a 2nd tank, manifolded, then later went to 2 100 pound tanks and alternated them. I added a commercial belt heater at one point. If you suck a lot of propane/butane out, it drops the pressure inside and the regulator isn’t magic - it is using spring tension to proportion input to output - lower in eventually leads to lower out.
I have one of the butane single-burner stoves like the one above. It works well. Available at Asian grocery stores in the ~$20 range.
For efficiency and compact fuel storage the MSR backpacking stoves (Whisperlight and Dragonfly) can’t be beat. They use Coleman fuel (white gas). I have the latter.
My all time favorite for quick use and serious efficiency is the JetBoil. Their canisters contain a mixture of propane and butane for decent cold weather performance. For small quantities of water (like for coffee or use with freeze dried meals) it’s unbeatable. It will boil a pint of water in a couple of minutes. They have larger pans available but I don’t own them.