you are right, large frames introduced in version BLE 4.2 are not supported in CYW4343W.
However, this is an optional feature in BLE4.2. Thus, it can be that device is formally compliant with BLE 4.2, but without large frames. Some discussion about the topic is here PSoC 62 + (BLE5 or BLE5-WiFI combo) software/hardware selection
I can note that 4343W also does not support data rate 2 Mbps. Thus, this chip looks somewhat outdated.
There is a newer chip 43012. However, some time ago BLE support of this chip was absent in development tools. I am curious whether this situation changed.
With best regards,
CYW4343W is BLE 4.2 compliant but does not support DLE feature. The datasheet update process is going on, we apologize for the confusion caused.
Yes CYW43012 is a newer WiFi-BT combo chip which is supported on ModusToolbox, AnyCloud, Mbed platforms.
Thanks for the responses, folks, much appreciated.