I never thought about making hot pluggable SMBus peripherals. It's an interesting idea. Many motherboards even have headers broken out, and of course operating systems already have drivers for many SMBus peripheral types. LoFi USB.
We have hot pluggable I2C at home. Every HDMI port (and pretty much every DP port with a passive adapter) has I2C on the DDC pins. The port also provides 5V 50mA so your MCU doesn't need external power. Example: https://www.reddit.com/r/raspberry_pi/comments/ws1ale/i2c_on...
