Your basic sources of 120VAC power are: pedestal, generator, and inverter.
Your basic sources of 12vdc power are: solar, battery, converter 120vac to 12vdc, alternator...maybe a wind device.
A fart converter would be a wonderment.
Each source has its positives and negatives based on your momentary situation.
All we are talking about is alternative sources of power. An inverter basically changes 12vdc to 120vac, providing a bit more 120vac from your batteries if needed. Obviously, it will drain the batteries fairly quickly.
Obviously, you could just use a generator to supply 120vac, but maybe their are times you don't want to use a generator but still use your tv or microwave.
Some tvs are powered by 12vcd.
Like any other piece of equipment, there are levels of quality and functionality (as to its load serving capabilities), and you can assume that your RV comes with an entry level inverter (minimal load serving capabilities) if it is part of your equipment list.
In fact, lots of things are cheap, entry level but get you off the lot until you decide you need more, maybe even an upgrade to your RV as you become experienced and wise up to what you really needed.
Even premium level units include some entry level batteries, converter, etc. to get you off on your first trip until you up-knowledge yourself.
Many people are eventually amazed they need quality power protection devices as an upgrade??? as far as I'm concerned they are necessities. Simple surge protectors are not enough.
Some inverters include a charger for your batteries. A charger will work off of 120vac.
A microwave can be hooked up directly to the inverter.
There really is no mystery to this.