It works but they pressure you hard nowadays to create an account when you use the app the first time. An account that you don't need if you have no Hue bridge. They once had a Bluetooth only app without all of these privacy invasion shenanigans.

They already made it pretty complicated to use the Hue app without an account if you just want to control Bluetooth enabled lights without a bridge.

I am also using Thunderbird since many years. I used KMail for some time but run into problems too often.

I use kruler in KDE.

Hottest day yet!