I was able to get this working using the guide here:
https://github.com/Joshua-Riek/ubuntu-rockchip/wiki/Ubuntu-24.04-LTS
I made sure SPI was installed on the SD card.
After that I made sure to install the OS onto the M2 SSD.
Afterwards I removed the root partition on the SD card and it boots, first to the SD and then the SSD takes over and the OS runs on the SSD.