I am not aware of a utility by that name and GBAMP is the name of a flash cart, one very popular among homebrew developers on the GBA, so I doubt Darkfader or tepples (both well versed developers in GBA stuff) would name a tool that.
If it is not on their sites ( http://www.darkfader.net/gba/ and https://pineight.com/gba/ respectively) then it likely does not exist, the second is missing a couple of things by way of the tetris game lockjaw and a music player for the GBA but no BIOS tools that I am aware of.

Equally I have not seen a GBA BIOS dumper with DLDI. The DS version of the GBA BIOS (basically the same and same in the ways that matter -- http://problemkaputt.de/gbatek.htm#dsbackwardscompatiblegbamode ), however I am not sure if it is dumped by the DS BIOS dumpers of which you have a couple of options for DLDI enabled dumping tools ( http://www.cryptosystem.org/archives/2007/02/libfatdldi-enabled-ds-bios-dumper/ http://filetrip.net/view?4WyqHhBcP8 ).

"bit-perfect match"
The hashes for it are well known.

 

This will work with EZ4. Just run it through your patcher to create the save file. It wasn't exactly designed for it, so you might get screen glitching, but once it goes green, it's done, so you're free to restart the GBA to dump the save to your SD. The save file will be the BIOS, though it will be too large. Half of it will be blank data. Just go in with a hex editor to remove the blank data at the end, which should be half the original size by the time you're done. Then just rename it to something like "GBA_BIOS.bin" and you'll have your own clean BIOS ready for use.

 

The one I posted will work on a GBA flashcard. Have only tried it on a GBA system.

 

It should go from yellow to a flashing green screen within a few seconds. The flashing green screen should mean it's done iirc.

 

I'm afraid I'm of little use here. All I can say is that it works fine on a SuperCard SD.

 

I worked out how to do it using this GBA Utility Tool from here: https://gbatemp.net/threads/gba-utility-tools-new-gba-application.353326/

For anyone wanting to use this with the EZ Flash IV cart, here are some instructions that worked for me:

For use with EZ Flash IV: (Works on original GBA, and probably SP, Micro and NDS)
(make sure you have updated the cart to the latest kernel. Check here for updates http://www.ezflash.cn/download/ )

1) Patch GBAUtilityTools.gba with EZ4 Rom Loader, pick the SRAM save size and save it to the SD,
click config, okay and then send.
(leave this file as just .gba)

2) Run it on GBA and follow the on-screen instructions, then turn it off and back on.
(THIS STEP IS IMPORTANT! as it will automatically dump the SRAM data back to the SD card, which will be you BIOS dump)

3) Switch off and plug SD back into PC, copy all these files to the hard drive somewhere (desktop?) [might not work straight from SD]

4) find the .sav file in the SAVER folder on the SD card root and move it to the same folder as the previous step.
(Will be named the same as the file you ran on the GBA)
[Should be around 32kb, if not try the previous steps again]

5) Run GBABiosFixer.exe in compatibility mode, choose Windows Vista, then drag the .sav file to the opened window and press enter
(it should just disappear, but don't worry it should have worked, if you cannot open the file in a hex editor in the next step, then try this step again).

6) Then open the same file (.sav) in a hex editor [DO NOT DO THIS IN NOTEPAD, IT WILL RUIN THE DUMP]
(I used this free HEX editor from here: http://www.chmaas.handshake.de/delphi/freeware/xvi32/xvi32.htm )

7) Delete everything passed hex 3FFF (not including)

8) Rename to GBA_BIOS.bin (file size should be 16,384 bytes)

9) Enjoy your legally owned GBA BIOS Dump!!