The open ecosystem around smart home has matured a lot in the last couple of years and Home Assistant now has millions of active users. There are also a wide variety of inexpensive sensors, switches, plugs, etc which come pre-installed with open source firmware like Tasmota and EspHome (example: https://www.athom.tech/tasmota). You won't find them at Best Buy or local stores but they're plentiful on Amazon, EBay and, of course, AliExpress.
To the extent companies like Google, Amazon, Apple and Samsung choose to support open, local-first standards I'll consider their devices as input and output nodes, however, I'll never let them be the central controller. There are now enough savvy open-only, local-first users that many of the Shenzen-based device makers have realized it's a profitable market segment and have given up trying to enforce their cloud-based apps. So we now have plenty of alternatives to the companies who only want users to be subscribers or eyeballs for ads.