There is one propane heater designed and approved for interior use, Mr Heater Buddy. About $90-$100 retail. It uses the 1lb disposable tanks and will burn about 4-6 hours depending on low-high setting. It can be connected via an extra hose to a bulk container but the instructions say not to use bulk containers indoors.

I believe the bulk container restriction to be a legal loophole. It would be safe to use a bulk container BUT it is possible that it would continue to burn so long that it could conceivably use all the oxygen or give off so much carbon monoxide as to make a small room unsafe. Get a battery powered carbon monoxide detector and ensure it is enabled when using the heater.

At the same time, make sure you have adequate air exchange in the space. The most common solution is to open a window just a bit to provide a source of fresh air to the space.

Alternates to the Mr Heater Buddy would be Kerosene heaters. They also give off "bad gas" and should be monitored with a carbon monoxide detector as well.

In both cases you should have a fire extingusiher handy. Kerosene heaters can be knocked over spilling fuel that would spread fire quickly. Propane heaters are open flame heaters and can catch billowing curtains, etc on fire. Make sure you get an ABC fire extingisher.

There are pros and cons to each. You may also want to think about alternate cooking sources at the same time. Some kerosene heaters can support a pot or pan on top to heat food and water allowing you to perform two tasks with one device. For lighting you could use the same kerosene and use oil lanterns like Dietz or Aladdin. They would help provide some minor heat as well as light. There is one model of Dietz lantern that will allow you to cook a cup sized pot at the same time. Kerosene has a long shelf life, 5+ yrs, if kept sealed and moisture free. A sealed 5 gallon gan should help you weather a week long power outage with ease. The issue may be where are you going to store fuel.

I already had a propane camp stove and liked the portability of the Mr Heater vs having to store a second fuel for a kerosene heater. In my case I have several propane lanterns, a 2 burner stove, a bbq grill, a torch (for plumbing repairs), and a heater. I have several of the propane tanks for the grill and a dozen or two of the 1lb tanks. I decided to standardize on one fuel source.

There are also freestanding fireplaces that are "vent free" meaning you don't have to vent them. Because there is no chimney, much more heat is added to the room vs a more traditional fireplace or vented gas fireplace. We have a natural gas vent free burner in our traditional brick fireplace with chimney. I keep the damper closed and most of the heat is transferred into the room. I can open the damper to help regulate the heat if needed.

It was able to keep our 2000 sq ft house around 55-65 F while outside temps were in the high 20's and low 30's during the last power outage. The room with the fireplace would be 65 while the remainder of the house was on the lower end. We used the Mr Heater as a room heater while in other rooms away from the fireplace. It claims it can heat 250 sq ft of space. I was able to teach my 6 yr old how to light the portable heater with the piezo electric built in starter button.