Just for anyone running across this later, another limitation of the EzFJr is that you have to load a custom F/w if you want SGB to work. The Krykzz cart works fine out the box for both platforms. That said, I do own both, and the EzFlash is a great budget alternative for handhelds if you can get it.
It’s absolutely a grand plan, and they’ve even written it all down. It’s called project 2025, and it’s their carefully engineered play by play for exactly this and more.