It doesn’t surprise me that replacement leather for your Acura isn’t available, because your TL is more of a mass-market vehicle, and as such the aftermarket for things like replacement interior and trim pieces simply isn’t there. They’re not really restoration candidates, and at nearly 10 years old, I ordering new parts from the dealer might be impossible and/or prohibitively expensive. An upholstery shop might be able to help you, but what I would suggest is a visit to your local salvage yard or specialty Acura dismantler.
You can pick up a complete interior (or the pieces you need) from a wrecked version of your car. I would recommend using sites and apps like Row 52 to search for likely donor vehicles, particularly so you aren’t chasing down the wrong color combination or sub-model. Also look at online auctions for salvage vehicles that you can pick up on the cheap. If you’re mechanically inclined and enterprising, you might even be able to get a wreck, pull the pieces you need and sell the remaining parts (or the entire vehicle hulk) for a profit.
If you don’t feel like doing the dirty work yourself, you can usually find people to pull parts for you. Also, before you make any moves, research Acura-specific Internet forums and/or talk to a specialist mechanic in your area too, because surely others have faced this issue. ~ Bill