You got it.
Basic primer:
LF implants operate at 125kHz, and they’re a legacy technology. They basically only have a simple ID that identifies them to doors and stuff (hence RFID). The xEM and half of the NExT have a special hacked chip that you can change the config and ID of which let’s you clone almost any access card onto those chips using special tools (like a proxmark)
HF implants are the evolution of the technology, and they can be read/written to with a smartphone (NFC). MIFARE was one of the first NFC protocols. It’s janky, doesn’t work with many phones, and has also been cracked like LF so you can change it’s ID if you use implants like the xM1. Newer HF chips are specifically made to be uncloneable for security, so many of those don’t have changing IDs, but they do have user memory where you can put URLs and a bunch of other data that will be read by any phone automatically when presented with the implant.