I was in a mood the other day, and went looking at tacky Christian cross pendants. There's a huge variety of them, from real Baltic Amber to cheap acrylic to sterling silver to hand carved mahogany. I started to dive deeper and found ones plastered with stars and stripes, and found ones covered with a big gay rainbow. So I kept digging and... I couldn't find one with a trans flag.
Sometimes I feel very, very alone as a trans Christian, and this was one of those times. I know it's tacky, I know mashing up religious iconography is problematic, I know that if it existed I wouldn't even want one, I know that a product needs a customer... And if there's no product, then there's no customer, and I don't exist.
You're either going to have to get one custom ordered or make it yourself. You are not alone. There are other trans christians out there. I've met a few.
People like you do exist. If there are no trans crosses listed for sale, its because there's not enough demand to cover the cost of a production run. Even you admitted you wouldn't want one.
Don't let capitalism get its tendrils so far into your mind that you think that you have to be a customer to exist.