Hello,
It is possible to create an hybrid application with Bluetooth LE and 802.15.4, we even have an application note that I believe will be helpful for you, you can check it in this link.
And,please take into account that the Mobile Wireless Systems (MWS) coexistence it's the module allows the coexistence of multiple wireless protocols.
In the latest SDK you can find and example in the hybrid folder called ble_802_15_4_fsci_black_box that you can find helpful for your development. You can find it in the following path :
<SDK installation path>\boards\frdmkw41z\wireless_examples\hybrid
Regards,
Estephania