[luma]

Any ZigBee or Z-Wave smart switches will be 100% local and just about anything you buy should be supported by Home Assistant.

Tested compatible Z-Wave device database: https://devices.zwave-js.io/ Same, but for ZigBee: https://www.zigbee2mqtt.io/supported-devices/

[stavros]

Don't buy anything that isn't Zigbee (or, I guess, Z-wave). Wi-Fi is much too heavy and insecure for smart home stuff, Zigbee has a ton of features you'll want (much simpler protocol, automatic repeaters, etc etc).

[JamesSwift]

More high-level Zigbee compatibility site: https://zigbee.blakadder.com