>>11969971
>That is completely insane. By that logic, could any random company manufacture their own copy of a PlayStation 5, sell it openly, and it would be "legal"?

Correct, this is quite literally what FPGA systems are.
Modretro have made a point of selling both an aftermarket Game Boy Color, and aftermarket games for the Game Boy Color or their alternative.
Analogue have made FPGA systems, but not games.

>Films are not video games though. They are not designed for specific hardware. You don't need a Sony DVD player to watch Sony films, for instance. You DO need a Sony video game console to play Sony games (as in, games intended to run on a Sony system, not games made by Sony).

Ah, but this is what formats are.
VHS, DVD, LaserDisc, Blu-Ray, HD-DVD, Betamax, are video formats intended for playback on certain compatible devices.
The original formats are protected products and can't be reproduced without permission (unauthorised copies, often bootlegs), but if you somehow produce a machine that can utilise the original formats to access the data, that's fine.
That's exactly the same case with video games, there's no issue with a device like the GB Operator, a USB accessory for PCs that can read the ROM and save data of Game Boy, Game Boy Color, and Game Boy Advance cartridges, make back-ups, and launch them in MGBA to play them on your PC instead.

A majority of earlier emulators do not require any special data such as BIOS to run software, which is not limited to ROM dumps of commercial games.
Some emulators do require BIOS for accurate emulation, perhaps things like firmware and decryption keys or to even run at all. Dolphin Emulator was maybe in trouble for bundling and distributing the Wii's common key, but this emerged so late that seemingly no action was taken against them.