Historically there were 24-bit ("16 megs") DOS extenders that would work on a 286, though the 286's inability to seamlessly go back to real mode (which is needed for compatibility with BIOS routines) creates issues that make 286 protected mode a bit of a theoretical curiosity.

I used the 286 in protected mode for developing the compiler, until the 386 became available.

They were really worth it.

OS/2 ran on the 286 in protected mode. Rational Systems had a 286 protected mode system that we shipped with Zortech. Pharlap had one, too.