Never fear, its (probably) possible if youre ok using 2 fobs. I just did this with the 9691t Schlage key.
-It is dual frequency, mine used 125khz RFID for the elevator, and 13.56 mhz NFC for my door.
-YOU WILL HAVE TO RETROGRADE YOUR FLIPPER TO FIRMWARE VERSION 0.79. THERE IS A BUG AFTER 0.80 THAT PREVETNS SCHLAGE KEYS FROM SAVING PROPERLY. I write it in all caps bc it took me a long time to figure that out. Very important lol.
-You can only write the 125khz RFID to the t5577.
-You can write the 13.56 MHZ data to a magic gen1a type tag, I found cheap ones on amazon. You want to see “changable UID” 13.56mhz, and either “1k” or “4k” depending on what the flipper says your tag is. I beleive it’ll be 1k. Cost me 7.99 for a pack of 10.
-Getting the 13.56 data is a little more complicated but not terrible. I assume your key uses mifare crypto1. If not, good luck. Lots of writeups on how to do MIFARE keys, but some tldr steps:
You may have to use the NFC detect reader function and your phone app (click “hub” at the bottom, mfkey app) a few times to decode your specific reader’s “nonces”. Then scan your key, and keep working on it until you can emualte and open the door. I got it with 30/32 keys, some people say they needed 32.
-After you get a good emulation (and youre on flipper firmware 0.79 or lower), go to: Applications > NFC > Nfc Magic > Write Gen1A, and write your changeable UID NFC tag.
I’m trying to figure out if I can recase both into a Schlage key case to avoid paying a lost key fee but thats another journey lol.
As for payment, pls donate $25 to the SPCA or equivalent deed.