These glasses have a LED. I haven't seen it for real, but I've heard it's not discernible at daylight.
Even so, it might still run afoul of German law. The German radio directive specifically forbids recording devices made to blend in and be surreptitious. The LED would have to be extremely obvious and hard to tamper with.
(It's not even a privacy directive; you're just not allowed to sell devices like that. Baby monitors have run afoul it.)
[German] https://www.bundesnetzagentur.de/DE/Fachthemen/Datenportal/V...
Blue is "online offers actioned/removed", orange is "legal proceedings initiated against vendors & sellers". That's more than 7 legal actions per day in 2024.
The LEDs can be disabled with a hardware mod.
https://thenewthings.com/p/i-paid-someone-to-hack-my-meta-gl...
You’re also not allowed to record anyone without their explicit consent if there is an expectation of privacy, even in public spaces. That makes the device use very likely to be illegal (assuming you use it to record videos in public spaces and it’s sensitive enough to record your surroundings)