I didn't even know you could put houses on the beach...
But to answer your question, no, the beaches on my island aren't big enough to fit a house.
They're barely big enough to fit random furniture the way I want them to be displayed... =/
I have my house in the south and yea it’s not enough space unless you don’t mind having furniture around your house. My sibling’s has more space then mine but only on the sides and not much on the front.
I was thinking about getting a second player and putting their house on the beach too, but also recently discovered that my west and east beaches are too small A house would only fit on my southern beaches, but I already have plans for those so I can't put a house there. I'm really bummed because I wanted to have a cute little tent on my western beach so bad
On the east side part near my peninsula, I think it can. I thought about putting one of my characters there, but decided against it since I have one villager house that's close to the beach.