One of the saves from here sounds like it'll do what you want:
https://gamefaqs.gamespot.com/gba/561559-the-legend-of-zelda-a-link-to-the-past-four-swords/saves
Just convert it using this tool:
https://savefileconverter.com/#/gameshark and remember to set the tool to output an 8kB save.
Sorry for the newb question, but once I convert it to the gameshark, how do I load it in mGBA? Is it a saved state through Retroarch? Is it a a new copy of the file called cartridge.sram that I found in the Hakchi saves folder for this game? I understand I need to convert it, and I understand that I need to convert it to an 8 kb file, I just don't know what to do with the finished file.
The save games I'm looking for seem to be in am 8 KB file called "cartridge.sram" located in hakchi/saves/CLV-A-XSTNT. I know this because if I delete this file or attempt to alter it, the games I already made through the GBA's save feature (That is, not a save state, emulator or Retroarch function, but selecting save in game) are gone.
I tried converting one of the gamefaqs files, converted it with the provided tool in 8KB format and I get a "C3: An error has occured." when booting the game on my NES classic, then the saves are empty.
I don't know if this is related, but if I try to alter which save state I'm using in Retroarch, the program freezes. I am unable to create saves in retroarch at all.
I'm trying to get this to work on mGBA through Retroarch Ozone on an NES classic.
Any help you could provide would be appreciated. My son has been looking forward to playing this game for over a year, but we don't own two copies of the cartridge, or two GBAs.