Sorry for bringing politics into this, but I love how this kind of stuff disproves the idea of capitalism being the reason people keep working on things. You can't tell me these guys started making Gameboy games because they wanted to exploit an untapped market. People love their random little meaningless projects and I'm here for it.
I think I'd consider this more along the lines of homebrew unless it gets an official, Nintendo-licensed release for the original hardware. Star Fox 2 is in a similar boat since Nintendo did officially release it in 2017, but only as a bonus for the SNES Classic and later NSO.
Covid caused them to skyrocket in price. But, there’s a big modding community now and you can do things like add usb c charging and a nicer screen.
Or, check out an SBCGaming community (here or elsewhere). Maybe get a Miyoo mini or an RG35XX. They can play up to and including PS1 games and are very portable and cheap.
Seems like they put some effort into it. Controls are responsive and the pixel art is good. It doesn’t have the telltale “sliding dialogue box” that all GB Studio games seem to have.