The SX126X support is a recent addition to the RH library.
The interface between the micro and the various LoRa devices does differ. The SX127X is configured via a bunch of registers, much like how you would address an RTC. When the SX128X was introduced Semetech adopted a different approach. You send a command byte and then a list of parameters. Semtech then adopted the same approach with the SX126X and LLCC68 modules.
Whilst it is possible to write a library where the API and sketches use the same format, there are subtle internal differences between SX127X and SX126X devices, there is not an absolute transparency.
My own LoRa library does support SX127X, SX128X and SX126X devices, and for pretty much all applications a sketch writen for one device type will work on the others, but not always ...........
I took a look at the new RH SX126X library file, but could not see any mention of the SX126X BUSY pin being supported, so I am not sure how the library can work without it. There appears to be no published examples for the SX126X.
In the latest release of RadioHead (version 128, posted Jan. 2024), there are three examples for the relatively new STM32WLX, which evidently has the SX126x radio embedded in the processor.
I've spent some time working with STM32 chips, the STM32 IDE and Cube programmer. That was more than enough.
1.127 2024-01-07 Added support for SX126x family radios, and also for the STM32WLE5xx and STM32WLE4xx families of ARM procedssors that have a SX126x radio built in, and as used in the LoRa-E5-HF module (which is used in WiO-E5 mini development board), the LoRa-E5-LF module and the NUCLEO_WL55JC1 development board. Tested with WiO-E5 mini development board, but no standalone SPI versions of this radio.
1.128 2024-01-12 Added missing sx126x examples to distribution.
Well, the code seems to be a long way from standard SX126X library codeto me, so it could be that any porting you did would be restricted to those particular devices.
I did try a couple of the E5 devices, based on the STM32WE5. They seem attractive at first since there is a processor as well in a module thats about the same size as a standard LoRa one. They are advertised as Arduino compatible, and I did manage to program them with a blink sketch, but I somehow I bricked them as well, just could not reprogram them again.
Their tech support forum were a long way from helpful, taking the approach that the internals were propriatry. I also discovered that they did not provide a binary of the original LoRaWAN firmware, so you could not revert the modules back to original.
