actually you can take a chip like the pP60 or P71 and load the mifare classic emulator on it and it will read as a 4 byte UID and a mifare classic chip, and respond to all of the ISO14444A transponder commands you’d expect… But also it will respond to APDUs and you can use a series of commands to get the chip to report its “real” UID which is a full 7 bytes. I believe the command is the same that you would use to get a chip with the privacy mode randomized UID feature turned on to report its real ID.