I'm familiar with and own most of the devices on obscurehandhelds.com and dingoonity, if that's what you're asking. They are quite interesting, but target different markets IMO so they're not 1-1 replacements. They give you an 80% experience across 7 different platforms, whereas original hardware w/ screen and battery upgrades give you 1-3 platforms at 100% fidelity.
The "RS-90" is the closest in terms of GB/GBA emulation, as it has an authentic GBA micro screen with 240x160 native resolution. Unfortunately the backlit TN panel, while impressive for its time, does not stand up to modern IPS panels. The devices on the market that do ship with IPS all have 320x240 resolution (or 320x480 half-height pixels, which amounts to the same thing), so you have to choose between a tiny image with borders on all sides or a blurry non-integer stretch.
Since I've set up my backlit GB, GBC, and GBA a few months ago, I haven't touched any of said emulation consoles. The fully upgraded original hardware ends up quite a bit more expensive ($200-$300 all in for console + screen + li-ion battery + flash cart) as compared to a $30 bittboy or rs-90, so they're essentially different markets. If you want the console to feel and look pixel-perfect, there's no replacement for the original hardware.