RenPy games are coded in python so they are mostly platform-independent. You should be able to launch the linux version on your rpi without needing to use the SDK but the SDK will always work regardless. For example, I'm on a Mac M1 which is also arm but it runs the Mac version compiled by lock on x86 without issue and don't need to use the SDK
edit: this doesn't work with the pc/windows version since it's a compiled x86 binary .exe file but on *nix OS' they use a shell script to invoke python directly so it should work fine