Unlike ram, ssds die after some use. So the lifespan of this device depends on this SD card, eMMC is basically a soldered SD card, a bad quality ssd. I have 3 old tablets with dead eMMC, they are otherwise perfectly fine devices, but unusable for anything
I’m not too familiar with the surface lineup, but iirc there are higher end devices with replaceable ssds. I think soldered ram is not a big deal in this form factor if it’s enough for the expected use case, but a soldered hard drive lowers the lifespan of your device