Let me clarify on how "ordering" a TRD Pro works cause I'm gonna guess no one gives a rats ass on pre-ordering any other 2019 model.
Ordering a TRD Pro is a misnomer. What you are doing is putting a deposit and being placed on a dealership wait list. Whether or not the dealer gets a pro is not up to the dealer but Toyota Corporate. If a dealer could order a pro they would order as many as possible to fulfill demand. Dealerships won't know if they get allocation(s) or not but generally due to past sales they have a good idea. They also won't know how many will get allocated.
It is best to work with a dealer that has a good history with selling a number of pros as this usually means their allocations are historically higher than others. But you also want to work with a dealership that sells as close to MSRP as possible so you dont get hosed - rare but not unheard of. Unfortunately, it may mean working with a dealership not local to you. Whether or not a dealership has a wait list open for deposits is really up to the dealership, not Toyota Corporate. Dealerships are also under no obligation to take a deposit. Many have had luck with finding a pro local to them but many have also had to go outside their region to find one. Good luck.