I want my phone to control everything through HomeKit.
I want my voice to control everything with Alexa.
My 'security' System is (Now) running through Google.

I use an old 'SmartThings hub to control Zigbee and Z-Wave devices.
I use HomeBridge to put everything under HomeKit.
I use a Starling Hub to convert my Google products to HomeKit.

... Everything in my house is now 'Platform' independent.

"Alexa.. Open the great room blinds"
"Siri... Open the kitchen Blinds"
"Alexa.. Lock the front door" (My front door is an Apple HomeKey lock)
My TV will display video from my Google Doorbell.

IMHO.. when you try to have 'one system to rule them all' you lock yourself into a corner.

(its why I've never switched to Home Assistant.. Its too complicated and when something goes wrong your wife will yell at you 😃 )