While I'm not sure about aptX (think it can be done by both hardware and software), LDAC is software based.
From Sony's website -
Sony - LDAC
"LDAC is compatible with a wide range of devices, because LDAC is a software codec."
From
Wikipedia - LDAC:
"The encoder of LDAC is open-source under Apache License 2.0, so that any device can be coded to transmit LDAC streams without patent or licensing issues. The decoder design remains proprietary."
"Starting from Android 8.0 "Oreo", LDAC is part of the Android Open Source Project, enabling every OEM to integrate this standard into their own Android devices freely."
Hence my previous request in this thread about adding support so that music can be encoded in LDAC and transmitted to say headphones or other receivers that already support LDAC decoding..