I have the same problem here, and i tried to make work with PS4 Reaper but with no success, I will post here my definitive solution.
I bought the physical media version but you can use a downloaded package if you want.
In my case, i need to dump the whole disc into my external hard drive, so i followed this guide:
When i get decrypted files into my HD, i've searched for the eboot.bin file and opened with a Hex editor, i my case i've just installed a Hex Editor in VSCode.
Then i searched by releaseL or gt7sp and i was found the follow pattern:
See the picture:
View attachment 312789
Then in my editor, i was changed the releaseL value to debug and reset the last words to 00 in hex.
See the picture:
View attachment 312790
Finally, i just saved the file, generate a new fake package and run into my PS4 with Hen. In the video guide that i was follow explain better the process of generating a fake package.
This is a definitive solution and debug menu will always active when you open the game.
In resume, you just need to do
1. Dump game base
2. Decrypt game dump, this is the easiest part in my opinion, you just need to follow the video steps
3. Open eboot.bin with a Hex editor
4. Search for gt7sp, releaseL or product.
5. After you find the follow pattern: gt7sp product and releaseL one above another
6. Change releaseL to debug and the last words from releaseL you need to make NULL or 00 in hex. Example: if is on release or releaseL, when you modify to debug your final word in hex will like that: debugsel, you just to make the word set to null or 00 in hex
7. Save the file and generate the fake package, again you just need to follow the video instructions to make these job
8. Install the modified package using Hen.
9. Enjoy your game with debug menu active.
Some Additional Info:
1. I was running into 9.00 firmware, but you can do it with another version, you just need to dump and recreate package
2. I reset the files because i think that this string is null terminated, and you need to be strict. I accidentally write debub instead of debug and the game doesn't shows up the file, make sure you write debug correctly.
3. Write in lowercase, don't be a fool to write in a uppercase please.
4. I don't tested with updates but i think that will work because a update file contains a eboot.bin
5. Don't mess around with the file otherwise it will won't work or will crash your game.
6. Delete your game when you being to install the package.
7. Double check your modifications before to package, you don't want to waste a lot of time packing and installing into your PS4 and seing that your modification isn't working. (I WAS THIS GUY. XD)
Sorry for the english!