Fast FPGA to HPS data transfer (write on RAM ?) on De0-Nano-SoC kit

DE0-Nano-SoC has 1 GB of HPS-side RAM and about 3 Mb (that's megabit) of on-chip memory.

It looks like the DE0-Nano-SoC package does not have any samples specifically showing how to use HPS-side RAM (which is odd, because my DE10-Nano has 3 different ones). You could grab the DE10-Nano package, take a look at e.g. the project in Demonstrations\FPGA\DDR3_RTL, and port the relevant pieces onto your board.

If you want to do this without interfering with Linux on HPS, you'll probably also want to read the instructions on how to prevent Linux from using part of your RAM, in the DE10-Nano user manual section 5.6. (The rest of that section has to do with a project that demonstrates the use of Nios II, which you most definitely DON'T need.)