Adding file data to the firmware file

[Redstonetill]

Hello everyone.
I am currently trying to fit a 500kB file into the 1MB Flash of the Spike Prime Hub. My idea for that was, that I just append to data to the firmware-base.bin file and later retrieve it inside a custom function in c (thought being, that the ram isnt being used to store the data).
For testing purposes I just added a little text to the end of the file Lego is nice pls work. I didnt change any of the values in the metadata file since I didnt think that any of them needed to be change (I think that because of the metadata.py file inside of tools directory of pybricks-micropython repository, but I didnt look any deeper into the "compling code". Just at the short description at the start of the file).
But when trying to "burn the image" onto the hub, I got this error:

RangeError: Offset is outside the bounds of the DataView
    at DataView.prototype.getUint32 (<anonymous>)
    at Ow (https://code.pybricks.com/static/js/main.1bf60dfd.js:2:550796)
    at Ow.next (<anonymous>)
    at Cw (https://code.pybricks.com/static/js/main.1bf60dfd.js:2:549482)
    at https://code.pybricks.com/static/js/main.1bf60dfd.js:2:552845
    at Nw (https://code.pybricks.com/static/js/main.1bf60dfd.js:2:552890)
    at Nw.next (<anonymous>)
    at Bw (https://code.pybricks.com/static/js/main.1bf60dfd.js:2:558892)
    at Bw.next (<anonymous>)
    at h (https://code.pybricks.com/static/js/main.1bf60dfd.js:2:1401964)

This is the firmware file I tried to "burn" onto the hub:
test.zip

Already saying thanks in advance if anyone can help me with this, since my is question is a little bit more "special"
Happy holidays

Added data to the file

[Redstonetill]

I think that I found the solution myself, I am just going to test it a little bit, but in HxD the data is in the firmware-base.bin and I can "burn" it onto hub

[Redstonetill]

So testing everything, it seems to work. So I want to explain how I did it for the prime hub.
First of all you will need to bring your file to the correct file name (this can be changed, but then the code I am going to publish here also needs to be changed). So the filename would be img.bin

Then you are going to create an empty folder inside of bricks/primehub called build. You can copy your file into this folder.
After that you will open the file bricks/_common/arm_none_ebai.mk. Scroll down till you see the line

# firmware blob without main.mpy or checksum - use as base for appending other .mpy
$(BUILD)/firmware-base.bin: [...]

You replace the whole "block" with this:

# firmware blob without main.mpy or checksum - use as base for appending other .mpy
$(BUILD)/firmware-base.bin: $(BUILD)/firmware.elf $(BUILD)/img.bin
	$(ECHO) "BIN creating firmware base file"
	$(Q)$(OBJCOPY) -O binary $(FW_SECTIONS) $(BUILD)/firmware.elf $@
# appending additional img data
	$(ECHO) "Appending $(BUILD)/img.bin to $(BUILD)/firmware-base.bin"
	cat $@ $(BUILD)/img.bin > $(BUILD)/firmware-base-with-img.bin
	mv $(BUILD)/firmware-base-with-img.bin $@
	$(ECHO) "`wc -c < $@` bytes"

When this is done, just compile the firmware like always and upload it to the prime hub. There shouldn't be any more problems