As @Devilclarke said, HiTag uses a challenge/response authentication,
I don’t know a lot about HiTag, so take the below with a pinch of salt
The xEM side in EM41xx mode has a 40 bit ID; HiTag uses 48 bit so there could be some issues there but you MAY be able to write more???
HiTag uses ISO14223
Also I am STILL GUESSING here, But Amal released the xHT to probably fill the gap, because there would be no real point dong it if the xEM/ NExT… ( T5577) could emulate the HiTag.
So wait to see if anybody else has some more concrete information for you, otherwise, I guess you have 2 main options
Give it a try ( and let us know )
Grab an xHT
I hope you find a solution