Also, you can apparently still get Afterburner kits. I remember those being a thing circa 2002; that was a custom frontlighting system for the original GBA.
I'm not sure how well it worked, but it's another way to frontlight a classic AGB-001.
The problem is, is that they're nearly impossible to find now. Besides, if you're going the frontlight route, you're better off ripping the light guide out of a gbasp instead, which would be significantly easier to source than an Afterburner kit.
Because trust me, I tried. It was actually how I stumbled on the backlighting, was by searching how to find an afterburner kit, and someone linked a chinese youtube link of the guy testing out his backlit gba.