develop and sell for latest consoles???

[iyenal]

Oh yeah... world of goo. That one is special.

Though... how do you plan a game variation within a limited playtime? Like world of goo... how did they design and fit everything into the timespace of play?

What do you mean exactly by timespace there?

This seems a good place to ask this:
Can I publish a new game using the engine of a past system with assets of some open source emulator so it can be launched for current devices?
Say, for example, a brand new GBA game for Nintendo Switch, but it isn´t just a "GBA style" game, but it is basically something that could actually run in a GBA by just ripping the .GBA file, running in a custom-made emulator for the new system.

Open source content can be used to make a commercial game, as long as the license permits it (or maybe needs an attribution). But you must own the rights of the engine to be able to commercialise a game developed using it.
And for running on the GBA, you can distribute INDEPENDENTLY from Nintendo the game by any way you want since you own the game's rights, but don't ask Nintendo to make the gba cartridges if you see what I mean. And I am not sure it's a good idea strategy speaking if you distribute it for free meanwhile paid on Switch.