There's not much reason to have 5GHz for smart home devices. 2.4GHz has better range and is ubiquitous. 5GHz has better throughput, but my lightbulb doesn't ne

There's not much reason to have 5GHz for smart home devices. 2.4GHz has better range and is ubiquitous. 5GHz has better throughput, but my lightbulb doesn't need 500MB/s of transfer. Most routers will just create two networks with the same name on both frequencies by default, which will work out of the box for 95% of the people. As other commenters have mentioned, usually devices can communicate with each other across those networks without issues.