I installed one in our "10 inch" floor drain and it did fit flat with the top of the floor. Guess it will depend on the exact size of your floor drain but it worked for mine.
We do not carry any stainless steel sink grates in house, however if you call us directly at 1-888-388-6372, a member of our sales team will be able to source a stainless steel sink grate for you.
Below is the closest drain strainer we have that might work. It is 7 1/2"" in diameter. https://www.etundra.com/commercial-plumbing-supplies/drains/floor-covers/commercial-7-one-half-inch-round-brass-floor-drain-strainer/
Yes, this drain cover is approximately 1/2" thick.
I am sorry, we do not have a 7 1/4"" size in the plastic floor sink top grates. I have attached a few other options below that may work. https://www.etundra.com/commercial-plumbing-supplies/drains/floor-covers/commercial-hinged-7-three-eighths-inch-square-brass-floor-drain-strainer/ https://www.etundra.com/commercial-plumbing-supplies/drains/floor-baskets/commercial-domed-7-one-half-inch-square-floor-drain-strainer-basket/ https://www.etundra.com/commercial-plumbing-supplies/drains/floor-baskets/commercial-domed-7-inch-square-floor-drain-strainer-basket/