Remote firmware update on Cyclone V or 10 without using embedded NIOS

Since my board does not include the Ethernet so I have go through this example on Cyclone V and Cyclone 10 device, where my board is with the UART communication

https://fpgacloud.intel.com/devstore/platform/16.0.0/Standard/remote-system-upgrade-over-uart-based-on-nios-ii-processor-with-epcq/

https://fpgacloud.intel.com/devstore/platform/18.0.0/Standard/remote-system-upgrade-with-system-console-for-cyclone-10-lp/

So far my application design have been implemented with RTL without embedded NIOS and the communication between software is through UART.

Now it left only the BUP part, so I think that it will be much easier if i can do it without the NIOS which I can differentiate between the normal communication and BUP communication.

Any advice? Thanks