"A 1/4 scale model was successfully demonstrated in 2022 in Narragansett Bay"[1]
Also I assume radar-proof is just because it's a ground effect vehicle that will never fly high enough to show up on radar it certainly doesn't look all angular like a stealth bomber. In which case my bicycle is also radar-proof?
They've done boat mode tests, but they haven't flown yet.
However to poke just a little fun this line stands out as a hilarious marketing claim that cannot possibly be true
"Almost all (98%) of UAE coastal residents are interested in riding a seaglider, according to our global consumer survey."
It's also interesting to note that the CEO has appeared on no fewer than 13 different podcasts between mid-2022 and last week which is I suppose how one would go about getting a high value US defence contract these days.