Yeh, I've used FunStock before, and always had a good experience with them. They seemed to stock all of the AT Games devices before.
Could it be possible that there is some kind of 'Atari exclusivity' in Europe for these retro devices that now, and it belongs to another company (Blaze)? Are the two Blaze consoles below for sale in the US?
https://www.funstockretro.co.uk/atari-retro-handheld
https://www.funstockretro.co.uk/atari-retro-tv-joystick