Looks nice. I would not call this "ultra low profile". That isn't really possible with mechanical switches. Even with mechanical switches, there are alternatives that are thinner, like the keytron/keychron line. The k1 would be the perfect keyboard for me, if it actually worked reliably.
Like someone else said, it's not easy to gauge the size of this one from the graphics on the landing page.
I'm considering a k1, what kind of reliability issues you're talking about?
I'm using an MX Keys with the Logitech dongle, it's slick without any lag (except sometimes when I have multiple Bluetooth connected things nearby + 20 visible Wi-Fi networks from my neighbors, then I can just make sure the dongle is closer).
But using the Bluetooth mode it's only as slick connecting to MacBooks, or to specific Wi-Fi/Bluetooth cards (AX201 is fine, The original Broadcom is shit).
Like someone else said, it's not easy to gauge the size of this one from the graphics on the landing page.