Nope.
The DSTWO is the only one, and it's more expensive than an Ak2i/R4i Gold RTS/3DS combined with an EZFlash - and the DSTWO's GBA support is pretty sub-par compared with the native support the 3-in-1 gives you.
The DS' hardware doesn't allow loading GBA code from the DS slot- it physically shuts off all DS-mode hardware (DS cartridge slot included) when it boots into GBA mode. The DSTWO has to get around it by embedding a much faster CPU of its own in its cartridge and using that to emulate the GBA. The DSTWO's GBA emulation really isn't all that great, though- more intensive games (Sigma Star Saga, for example) take a severe hit to playability thanks to the frameskipping. While almost every game works
fine, it's definitely a noticably inferior experience to playing it with native hardware. The downside of the on-cart CPU's that it continually draws extra power- meaning your battery life takes a significant hit when actively using it (worse if you have to overclock it to run awkward GBA titles at playable framerates), and it continues drawing power when the system's in Sleep Mode- meaning it's practically useless. I've got one, and I wouldn't recommend the experience- it's only really desirable if you're on a system that just doesn't have a GBA slot to use a passthrough card with.
The only way to access the DS' native GBA support is with a Slot-2 flashcart. The 3-in-1 is unique, in that it's fitted to the DS Lite's form factor, and just exists as a passthrough tool to accept code from the DS slot when prompted by its loader software (AKAIO/Wood), and then load as if it were a real GBA cartridge. There are other Slot-2 flashcarts, but the only other one actually worth using is the EZ-Flash IV - and that's the wrong size for the DS Lite. Just about every single other Slot-2 flashcart is a miserable experience.
It's pretty bad. Once again, the picture just isn't the right size for the DS' screen- you're stuck with cropping the screen, or scaling it. Both of them are pretty rubbish solutions. The same issue exists with NES emulation- you can either slice off large sections of the screen and have to pause to adjust what's hidden where necessary during gameplay, or get by with a scaled version of the output- which makes it look horrible.
As for which MD games work?
here's a compatibility list. Note the awkward workarounds necessary for a lot of games- those games that do run are often quite glitchy, and Sonic 3 and Knuckles won't even boot without manually patching the ROM to get around the 3MB size limit.
It's 2016. Emulating this stuff on the DS is just a horrible, entirely unnecessary chore. Emulating anything other than GB/GBC/GBA games on the DS is just a curiosity, really- the screen resolution is too low to be useful for much else.
The DS' hardware is eleven years old, and it was pretty low-end even then. If you absolutely must be able to play MD/SNES games, just get a controller clip for your smartphone, or a Android gaming handheld- the GPD XD is pretty impressive.