Well this changes the context somewhat, as @beegee noted, the numbers are radically different now.
Well mostly because I’m not @carlrowan or a staff member, just a groupie. And I prefer the Microchip Power Debugger on my desk over the PPK2 which is in a box somewhere but is definitely better than the STM Power Shield, oh the irony.
Same for everyone, the STM32WL55 in relative terms is brand spanking new - no one has more than a couple of months experience with any commercial variation of the chip, from ST or anyone. That is assuming they have managed to get their hands on any, I started out with 433MHz ones as I could get two and nothing else at the time.
If you’ve got the RAK811 under control, you don’t have to rewrite anything.
But you can follow the link above to download the difference files and use the official ST STM32Cube MCU, you’ve got access to the ST point to point code that you can put on the modules.
It’s early days for the module, they have to start somewhere. Taking the Cube code base and getting up & running with an AT interface that suits your need wouldn’t be a big job for you - couple of days tops.