Hi @Egodomenico ,
For custom firmware, we have a guide on RAK3172-SiP documentation. This one uses RUI3 firmware framework and Arduino - RAK3172-SiP Module Quick Start Guide | RAKwireless Documentation Center
If you look for STM32CubeIDE for RAK3172-SiP, we do not have it but you can try our guide for RAK3172 - RAK3172 Module Low Level Development Reference | RAKwireless Documentation Center
By using STM32WL SDK v1.0.0, you can try to use these radio files for modification (RAK3172 and RAK3172-SiP have different radio frontend) - Dropbox - RAK3172_SIP_radiofiles.7z - Simplify your life
Please take note that we do not really support examples provided by STM32 for STM32CubeIDE since we have no access on its development.
We can support you on RUI3 though.