I’m still intrigued by there Philippines if that counts as SEA. Even though it seems like there are very few luxury hotels.
Other than that, it seems like SEA simply doesn’t have great beaches.

I went to Corsica last week and the water was crystal clear. The food is amazing, people are friendly and it’s safe.
The front desk agent who checked us in told us he’d been to the Seychelles and he didn’t understand all the fuzz as the water looked just like in the Corsican village he’s from.
I didn’t know a place like this exists in Europe - it was better than the (admittedly, small) parts of the Caribbean I’ve seen. As I’m mostly based in Europe, I can go to Corsica (or maybe Sardinia or Montenegro) and save money on flights. Admittedly, there aren’t many luxury hotels in Corsica, but you don’t have to worry about safety, food poisoning, denghue etc. - 4 star hotels or AirBnB’s are perfectly fine.

In retrospect, Southeast Asia seems like a massive waste of time in that regard - at least when traveling from another continent. In European winter, I’ll probably go to the Maldives or the Caribbean or something like that for a beach vacation, but definitely not Southeast Asia.
Don’t get me wrong, I LOVE Asia, but the beaches have been disappointing.