I know that you posted this several days ago, and it may no longer be relevant, but I thought that I’d go ahead and reply anyway.
In another life, (from about 1988 – 2003) among other things, I used to sell and install pellet stoves, occasionally serviced them, plus supervised the service techs that serviced them. So I know a little about them.
The link that Dale posted is fairly good for general info about pellet stoves.
As for dealing with them in conjunction with home inspections, essentially, my bottom line recommendation would be this: " In order to determine the safety and functionality of the pellet stove, recommend full evaluation by a qualified hearth professional with specific knowledge of pellet stoves". I worded it that way, because a typical HVAC tech, as well as a typical certified chimney sweep, will probably be clueless when it comes to pellet stoves. Pellet stoves are somewhat unique, and can be a little quirky. You’re essentially dealing with a stove that’s burning a bio-mass product, like a wood stove, but yet it depends on mechanical, (usually 3 motors, 2 fans) as well as electronic components (hi-limits, circuit boards, etc) in order to function.
You could, I suppose, try to light it, but some of them have to be lit by hand, much like a wood stove, usually with gel starter. I don’t believe too many of us light wood stoves in he course of a home inspection, or am I mistaken? Other stoves do light with electronic ignitions, but if the burn pot hasn’t been cleaned lately, it may not light properly or at all. If it had run out of pellets, even if the hopper had been refilled, but the stove hadn’t been “primed”, it won’t light. Regardless, you’ll still end up recommending evaluation by a specialist.
One of the nice things about pellet stoves, is that they are relatively safe. If anything at all goes wrong with any of the systems, the whole unit will shut down, sometimes gradually, sometimes immediately. In the latter case, some smoke may enter the house, but normally it is minimal. The clearances are relatively close. Most units only need 1-2" to combustibles on the rear of the stove. Usually 8" on the sides. The pellet pipe only needs 3" to combustibles and can go directly out, horizontally through an exterior wall and typically only needs to clear the house by 12".
If you had the manual to the specific model you were inspecting, and you wanted to take the time, you may be comfortable making a determination that at least it meets all of the required clearances. You would want to be certain, however, that a homeowner ( or other unknowledgeable installer) hasn’t installed an incorrect pipe, such as single wall, wood stove pipe, instead of true pellet pipe. I have seen this done, and if you don’t know what you’re looking for, or don’t look closely, it can be easily missed.
This got a little long winded, I see, but in answer to your question, no there really isn’t a way to truly determine functionality without lighting it. A knowledgeable tech could evaluate each of the individual components, to see if they are giving the correct readings, but eventually, it has to be lit. Refer it to a specialist.