Mines are not outdoor rated, they are just bulb behind (don’t know the word in English) https://duckduckgo.com/?q=applique+extérieure+lumière+&t=fpas&iax=images&ia=images
Here is one outside rated (but should have more available) https://www.bestbuy.com/site/philips-hue-white-welcome-outdoor-floodlight-black/6326654.p?skuId=6326654&intl=nosplash
It is normal behaviour to have them locked to 2.4ghz (just like any other wifi smart things). And it is better that way as 2.4ghz has a longer wifi range than 5ghz.
You can check here if a solution suits your need https://www.home-assistant.io/docs/energy/electricity-grid/