Do you mean offer a Silicon Labs EFR32 core platform for ESPHome using Zephyr (RTOS) codebase or similar for use on hardware like the Z-Uno (Z-Wave development board)?
I would love to see that but personally believe there is a larger usebase that would want Zigbee and/or OpenThread + Matter support in ESPHome, and unlike Z-Wave, there are ESP32 models with buiilt in Zigbee/Thread radio (and some peope are working on Zigbee and Thread support for ESPHome).
Anyway, while the use case for Z-Wave might be niche and I do not have the skills to help with that I could see that maybe being technically possible considering these referenses linked here below that show someone working on Zephyr for ESPHome (though for a different platform) and Silicon Labs working on Zephyr support for EFR32 (which in theory could include their Z-Wave radio MCU SoCs), but the main challange would probably be to first convince Silicon Labs to make a Z-Wave library that could be used with it: