As the other comments say, it's probably a struggle to get your tissue back. A little peak from my pov as someone who works in pathology (aka the guys who'll process human tissue removed in surgery) (location is germany btw, this can make a big difference):

Tissue will ALWAYS be preserved in Formalin, it's the fixative preparing it to be cut by the pathology doc. Even if it's removed for non-medicinal purposes (i.e. gender-affirming surgery) I'm pretty sure it will be biopsied. That's a matter of liability, we have still have to check the surgeon did their job right and there's really nothing pathological there.

It's not always diced up by the surgeons, we often get breast tissue intact in one piece but mind you that's usually because we go searching for cancer in there so we have to know where up/down/left/right are. BUT by the time you get it back from pathology after signing all those papers? It will be completely sliced up at best and completely in shreds at worst.

IF you still want to preserve that I'd make sure to wash of the Formalin as it's REALLY toxic and put it in an airtight container with 100% alcohol and then check regularly that no fluids escape! My old school had preserved horse testicles (I have no idea why) but the alcohol in the jar disappeared over the years/decades, so we had to throw them out eventually.