Altera's MAX10 remote update
OK, i have just spoke to the local support.

So no problem in just using internal flash. The CFM should be enabled while creating the flash IP core- by default it is hidden. This is also the place to look up the base address to start writing the image.

The image is .rbf file generated by Quartus (probably out of .sof, i haven't tried it yet). 

Last- to start running the image the FPGA has to do external reset. This is a little upsetting because i haven't prepared it in hardware, but i think i saw something in documents hinting that it's somehow also available from inside the FPGA. Will update if i find it.