All Moteinos come with the Dualoptiboot bootloader. That means that if you find a way to transfer a new compiled HEX firmware into the external 4MBIT flash, Dualoptiboot will pick that up and replace the main firmware with it upon a reboot.
The RFM69 library has some extensions that provide that functionality with RFM69 transceivers.
But I have never created or maintained a library for RFM95/96 transceivers, I just offered them with Moteinos.
In the other thread you posted, I mentioned that if you came up with a way to make that HEX transfer then the built in Dualoptiboot bootloader would handle the rest, on all current Moteinos including the SAMD based M0.