Maneschewitz makes a macaroon pie crust for Pesah.
The problem with Key Lime Pie is that I never once saw condensed or evaporated milk with an acceptable Pesah hechsher. I could be wrong and maybe one of the heimishe companies makes it.
Ka mashma lan, from my grandmother, a”h, to make a crust with pistachios, sugar, potato starch and egg whites (She was Syrian, and made lots of desserts on Pesah with pistachios, walnuts, dates, etc.)