Yes, though sharing BLE with other protocols is challenging (even with first-class citizens like ANT+ there are various caveats). The proprietary protocols are Shockburst/Gazelle [0] which are based of the ancient nrf24 setup.
Having said that, the radio peripheral on the chip is dead simple to drive bare-metal. Create a packet (with the convenience function), put its address in a register and hit the 'send' bit (more or less, glossing over waiting for ready bits here). Receiving is as easy - point to where you want packets to land, go into RX mode and wait for the "packet received" bit to be set.
Having said that, the radio peripheral on the chip is dead simple to drive bare-metal. Create a packet (with the convenience function), put its address in a register and hit the 'send' bit (more or less, glossing over waiting for ready bits here). Receiving is as easy - point to where you want packets to land, go into RX mode and wait for the "packet received" bit to be set.
[0] https://docs.nordicsemi.com/bundle/sdk_nrf5_v17.1.0/page/exa...