From a quick look online it may be the Pixel 8 https://www.gsmarena.com/google_pixel_8-12546.php at 150.5 x 70.8 x 8.9 mm based on recommended devices.

Maybe an old Pixel with an old version of GrapheneOS, but at that point you're losing most of the security benefits and, depending on your goals, you may be better served with a small phone running a different OS