From what I’ve read, I gather the issue is that it’s more expensive to get the eMMC version because you can’t install the OS directly there. You have to use a “Compute Module 4 IO Board” (40 extra bucks) and even then, if you flash the eMMC with the new OS, the SD card is inaccesible so you won’t be able to use an SDCard as storage (Ckeck post 10 && 11 in this discussion uConsole with 8GB RAM/ 32GB EMMC - uConsole - clockworkpi)
The thread is old tho (2023), so it would be nice to know if someone has tried it with any level of success. Maybe with the new OS Images and updated kernel. I decided to specify a No-eMMC CM4 just to be on the safe side 