My reluctance with Ubuntu Raspi come mainly from my failure to build the RT code. Tried many times with different Ubuntu Raspi versions. The repository felt like a work in progress.
By contrast, the Bookworm OS compiled easily, although I still have issues in deploying the kernel. I have the RT working, but not the same way as my X86.
AK may still support both Ubuntu and Raspberry for the Pi for the 64 bit version. Not sure if there is any need for the 32 bit version?