Thanks - I was just thinking out loud though. The Sear Plate did work for Frozen, but it's perfed so I just thought the existing piece of seasoned steel may work (for fresh). It's 20lbs, 19.5x19.5 - I'll try it one day. Otherwise I already have a few pizza stones I can use. It's not so much the cost of acquiring something new, it's the storage requirements of the new thing(s).The concept of a steel plate (or cast iron) is the retained energy in the plate. The Grill Grates will not have as much retained energy as a 1/4" or thicker steel plate. However, aluminum transfers heat much faster than steel or iron. Some of the guys on the pizza forum experimented with aluminum and it was just too fast. The pizzas were burning before they could cook the toppings.
The RecTeq griddle may work out. It's not as thick as the plate I used, but it may be adequate. Only way to tell for sure, is to try it. I was running in a common home oven at the time. It was capable of about 525F and that's where I ran it. I let it heat up for an hour then threw on a pie. I'd wait until it came back up to temperature before loading a second or third pie. I made some tasty NY style pies on that plate.
If you go on amazon or google you can find "baking steels" or "pizza steels" all over. Thicker is better as it has more retained heat to cook for the time needed. I'd recommend at least 1/4", thicker is better. Avoid stainless steel as the thermal transfer rate is half of regular steel or cast iron.
Here's a cheap one. https://www.amazon.com/Steel-Plate-A36-0-25-Thick/dp/B081Z3FKQM/ref=sr_1_30?crid=4RM8JNA00OWK&keywords=pizza+steel&qid=1658957436&sprefix=pizza+,aps,157&sr=8-30