EZFlash Omega?
What's that? Never seen one seeling in Euroland.
Or is that one of those "gone before even release" type of flashcards?
Was around for a while.
The EZ4, which was the last of the standalone GBA slot era of DS flash carts (which also played GBA games) that was any good and only one available, got really scarce at one point. They came back with a tweaked model called the reform which was basically the same again. However in the years since the EZ4 was designed the chips to make it in turn got scarce.
To that end a new line of carts was made using modern chips and approaches, somewhat to match the everdrive gba x5
https://gbatemp.net/review/everdrive-gba-x5.489/ that was rising up at the time.
This was known as the EZFlash Omega, and was actually really quite shiny if a bit power hungry at times (though updates brought that down a bit to be roughly in line with commercial games and some other flash carts). GBA on the EZ4 was able to do most of the library quite happily,
https://gbatemp.net/threads/buying-a-gba-flash-cart-in-2013.341203/page-18#post-4756995 , even gaining SDHC support and onboard patching around the time of the reform in an unexpected update
https://gbatemp.net/threads/ez4-kernel-2-03-soft-reset-and-sleep-improvements.477690/ , but was always focused more on the DS side of things. This was a nice fast loader, aimed at having basically all of the GBA library available with super fast loading, savestates, cheats, soft reset and more that the EZ4 (but not the even older EZ3 and EZ2) struggled with.
https://gbatemp.net/review/ez-flash-omega.795/
https://gbatemp.net/threads/ezflash-omega-gba-flash-cart-in-house-at-gbatemp.500357/
It stuck around for a while and was pretty popular. Don't know what Euro sellers are still standing and might stock them but was around worldwide, and enough to see some extra colours of shells released (
https://gbatemp.net/threads/ezflash-announce-orange-omega-case.552711/ ).
Following that what was supposed to be the final word in GBA flash carts saw a new hardware version with its own kernel and whatever else called the EZFlash Omega definitive edition. It added a few more things, including rumble and the ability to play GBA videos that were previously unplayable (
https://mgba.io/2015/10/20/dumping-the-undumped/ ).
https://gbatemp.net/threads/ezflash...on-gba-flash-cart-in-house-at-gbatemp.581991/
They also put out a GB/GBC flash cart called the EZFlash Junior, also with modern chips and aimed at being a game player's flash cart (most other others being aimed at homebrew use and not doing so well for having a library of commercial games to play at your whim).
https://gbatemp.net/threads/ez-flash-junior-testflight.558875/
They also open sourced a bunch of their stuff
https://gbatemp.net/threads/ezflash-omega-source-code-released.510348/
https://github.com/ez-flash/
Which in turn saw some users do some stuff with it, most looking first at Sterophonick's efforts here
https://gbatemp.net/threads/new-theme-for-ez-flash-omega.520665/
https://gbatemp.net/threads/make-your-own-rumble-game-for-ez-flash-omega-definitive-edition.580909/
https://gbatemp.net/threads/new-open-source-gba-shoot-em-up-butano-fighter.576952/#post-9353543
https://gbatemp.net/threads/ez-omega-with-pogoshell-alpha.510778/
https://gbatemp.net/threads/ez-flash-omega-disc_io-library-project.511490/
https://gbatemp.net/threads/ez-flash-omega-kernel-with-spanish-language.510592/
And thus we have the history of the GBA scene since about 2013.