Not sure… check out this thread - https://forum.dangerousthings.com/t/chip-compatibility-with-systems-and-devices
Not with the xNT. Assuming you read the thread linked above first… the ability to clone means the target chip must allow the UID to be changed… the xNT has an NTAG216 chip inside which does not allow this, so you cannot clone another chip’s ID to the xNT… but you might be able to enroll the xNT into the system though.
However, you stated that residents get “a little blue key fob” which may possibly mean it’s a 125khz EM based system… the major percentage of “little blue keyfobs” are 125khz EM… but it doesn’t always mean that. If that is the case though, then you could possibly clone one to our xEM implant… or just enroll the xEM if you don’t have access to reliable cloning hardware.
Both xNT and xEM have ID numbers that are typically used for access control of some kind. The xEM can change it’s ID while the xNT cannot. However, the xNT also has user programmable memory and is NFC Type 2 compliant. These devices are like golf clubs in a bag or paints on a pallet. What you can do with them is up to their features and what you can do with those features.