I feel this way about the GBA. It's modern enough to offer things like a 32-bit pipelined CPU that can be targeted with a modern C[0] or Rust[1] toolchain, but you are still extremely close to the metal. Even decade old PCs can run emulators that focus on accuracy rather than raw performance, and the physical AGS-101 has pretty nice backlight without any mods. Plus many of the games have aged extremely well, with the graphical style of e.g. Pokemon Emerald still being closely followed in modern indie games.

[0]: https://gbadev.org [1]: https://docs.rs/gba/latest/gba/