I would think it would be cool to use a drone to get to hard to reach areas on larger layouts and do some filming.
If you are going to stay inside there are some very inexpensive sUAS quad-copters that take video. A little more money can get you streaming to your smart phone.
Make sure you get one with altitude hold (usually pressure sensing). If you don’t you will have lots of crash landings into your trains.
Also, even a small indoor drone produces a lot of down draft, so if you did not glue your ballast down it will be blown off the table.
I have thought about using my large sUAV I use for search and rescue training to film my layout’s progress, but it would blow my trains off the table.