Well, of course, you can just wear sunglasses indoor too. Generally speaking, as we know that there are many people who wear sunglasses for good looking, and fashionable feeling. And actually wearing some sunglasses will just show the personality and make the wearer look cool. But on the other hand, sunglasses can protect your eyes from strong sunlight and uv rays when you go outside. But also, you can just wear them indoor too. It can be fine. While, you should not always wear them indoor, for it will just make your eyes weaker.
As a matter of fact, currently, sunglasses are not confined to indoor use, a lot of people wear sunglasses just want to appear more attractive and remain mysterious, which could make them cool. Of course you could also wear sunglasses indoor, though it would be quite weird in the first place, but that is quite a popular practice nowadays.
There is no harm to wear sunglasses indoor, but don't wear sunglasses indoor for so long. Sunglasses are made for shield eyes from radiation and sunshine, so when you surf the internet, you can wear sunglasses to keep your eyes away from radiation.
However, it's not a good idea to wear that for too long, because, we need to stay in natural light which can keep our eyes healthy, basically.