If by the “Sonoff 8 Button Remote” you mean the SwitchMan R5, then unfortunately you cannot clone your third-party RF remote into the R5.
The R5 does not use standard 433 MHz RF. It uses SONOFF’s proprietary eWeLink-Remote protocol, so it cannot learn the RF codes transmitted by your awning remote. For a conventional 433 MHz remote, an RF Bridge is indeed the appropriate device.
However, you can use the R5 with iHost without an RF Bridge. iHost can act as an eWeLink-Remote gateway, and R5 is supported as a sub-device. Once paired with iHost, the R5’s buttons can be used to trigger scenes/automations and control devices that are available to iHost.
One important detail: if your awning itself is controlled only by that proprietary RF remote and has no smart interface, adding an R5 to iHost won’t make the R5 control the awning directly. You would still need some way for iHost to send the appropriate RF command, typically an RF Bridge, assuming the awning uses a compatible 433 MHz protocol.