I just thought of something. Don't the K1 GBA devices contain the original GBA BIOS, and would therefore technically be illegal to produce? Nintendo could possibly prosecute them if they think it's worth the effort.
I wish the CPU was faster to make emulation capabilities more comparable to the Dingoo. If it could run SNES games, it would be great. It's still pretty good at this price, over here it's hard to even get a used GBA SP at that price, and GBA flashcarts are getting hard to find as well. Plus the fact that it supports multiboot so it's possible to use it to play Zelda Four Swords Adventures makes me kind of want one, even though I have plenty of devices that can emulate GBA well.
So the answer to the topic description is yes, it's definitely worth buying if you're a fan of retro games like me and you don't already have several handhelds that can emulate GBA games.