To be fair, microkernels are also highly successful in embedded devices and auxiliary processors. It’s just that you don’t usually directly interact with them. For example, Intel ME runs MINIX, and Apple’s Secure Enclave Processor runs L4. Also most OSes these days have some kind of hypervisor/secure monitor that’s more privileged than the regular kernel: TEE on Android, SPTM on Apple, VBS on Windows, and proprietary ones on all the game consoles. They vary in how much functionality they’re actually responsible for, but if it’s a significant amount then they tend to have a microkernel-ish design internally.

Another example of microkernel-based systems you do interact with is car infotainment systems, where QNX has apparently seen a lot of use – though I think these days it’s being displaced by Linux and Android Automotive? I don’t actually know much about that industry.