I'm trying to emulate an NDEF tag on an abstract embedded system so, I have questions about NFC technology. Why some NFC chips can't emulate NDEF tags? If my chip doesn't support a card emulation, can I hack it somehow to fake it by using APDU commands?
If it is a CR95HF then a quick read of the datasheet because I've not used this particular chip before, suggest that like other chips I've seen that it is true that it does not support ISO7816-4 because it is not designed to work at that high level protocol level.
If you look at the picture it's working at the "protocol" level which is one level below ISO7816-4 which is fine, it can transmit/receive data at the NFC A/B protocol level but it is up to the Host's CPU to decode the raw frame data in to ISO7816-4 commands and data.
But this is not your problem, even at the lower protocol level it does not seem to be able to handle both sides on the communication.
I suggest you read https://stackoverflow.com/a/65659726/2373819 as it give some background to hardware capabilities, as the datasheet says it's "Operating modes supported:– Reader/Writer" then it is only an "initiator" and I see no signs that it can be a "target" and therefore it cannot emulate any Tags.
So in short that hardware is not capable of emulating any type of NFC Tag
