Here's the first
thing that I would do ... talk to your supervisor!
Think about it ... right now, you serve
geeks. Now, for whatever crazy reason, you wish to become
Your supervisor certainly is in an excellent position to know where the geeks are ... what their teams need ... and how you might possibly transition into them ... and
to give you experienced pointers.
Your supervisor is also
in a superior position to talk you out of it!
"Bloom where you are planted."
... and, "be willing to be an apprentice."
Obviously, the most-logical place to begin your (perhaps initially, "provisional") foray into the world of pure-programming at your company would be one that leverages, as much as practicable, your existing
experience as a sysadmin. It might, therefore, be an intermediate step. Your supervisor will either be in a position right-now to guide you, or (s)he will be able to connect with someone who can.
Enjoy the ride.
And ... "believe me, this sort of thing happens all the time." Sometimes it works out, sometimes it doesn't, but "it's all good." You want to grow.
Maybe. Maybe not. We'll see. (Either way, you won't
get fired and don't
have to cut-and-run.) "Anyway, cool!"