For bspwm, where all it’s functionality is exposed to shell commands it can very narrowly achieve something similar, but again, Karibiner’s scope of operation is all apps system-wide.
What people are wishing for when they wish for “a karibiner equivalent” isn’t a hotkey mapping app per se — there’s obviously dozens and dozens of half-baked versions of those. What people are actually wanting is a system for setting globally-consistent keybindings such that they can set it once and universally every app respects it. That would require either a system wide protocol for agreeing on keybindings no matter what wheel-reinventing UI/desktop toolkit an app was built in, or an Uber-keybindings app that knew how to write defaults to the 20 different preference files that control this stuff for different toolkits.
That's why bspwm uses a WM independent tool for all keybindings:
https://github.com/baskerville/sxhkd