You'll have a hard decision in a case like this. Assuming you're legit, there are extremely low odds of it being actual SWAT with a no knock entry and raiding the wrong house. However it's highly likely you will die if you fire on them. On the other hand it's higher odds it's criminal imposters with lower odds of them killing you if you fire on them. Also how quickly can you retrieve your firearm?
I'd barricade myself in a room or flee and call 911.
This has happened before, with I think a swat officer getting shot and killed. The homeowner wasn't shot If you're going to execute a no-knock warrant, you had better damn make sure you got the right house. Regardless of who gets shot, the cops or the homeowner or BOTH, it is a really shitty situation to be in (if it's real swat). That being said, like you mentioned, there are much higher odds that it's imposters.
Barracading/fleeing is great if it happens to be a possibility.... firearm isn't always a possibility either. I think it really depends on the situation. If you have a guy at the front and back door, and if your interior doors/locks are shitty (99.99% of the time they are), those might not be good options. Especially if you dont have much time.If you can do so quickly, I would retrieve the firearm for self defense purposes
first, then consider finding a hiding spot and calling the cops. Because if they intruders find you, your hiding spot and the police aren't going to save you.