Launched in the year 2022, the 65GGU7900B is a 65" 4K TV from Grundig. It features a 10-bit IPS panel. It can achieve a max resolution of 3840 x 2160 @ 60 Hz with a pixel density of 68 ppi.
Picture Quality
After screen size and resolution, the next important specification of a display is its Color Reproduction, which is defined by its color gamut specification.
This TV doesn't come with a color gamut specification, so we have to take a guess.
Now, since the TV features a 65 inch screen, it won't come with a cheap panel, so here we can assume its equivalent sRGB coverage to be 90-100% or above. Undoubtedly The color quality on this TV should be Lifelike! It is capable of producing accurate colors.
Understanding Color Gamut
Color gamut specification of a display indicates the range of colors that the TV can display.
In other words, it determines the ability of a TV to produce accurate colors. A display with low color gamut coverage will miss out on some colors (such as deep red), thus producing a "washed out" picture.
It is specified in different units - sRGB(most popular), NTSC, DCI P3 to name a few. It is upto the manufacturer which one they choose.
But don't worry, below is a chart that you can use to choose a TV with good color accuracy.
After color gamut, you should look at the static contrast specification as it impacts the picture quality substantially.
The importance of static contrast ratio
A TV with low static contrast ratio will not produce deep enough blacks and can bleed backlight as below:

The above TV's static contrast is 800:1. So make sure you get a TV with a static contrast of >= 1000:1. Ofcourse, More is better.
Think of static contrast as another dimension to details — just like resolution. To put it into perspective, a TV with low contrast ratio will produce less shades of colors, thus lesser detail overall.
If given a choice, always prefer a FHD TV with high contrast ratio over a 4K TV with low contrast ratio.
However, we couldn't find a static contrast ratio specification for this TV. Once again we have to take a guess based on the TV's other specifications. FYI — IPS panels come with a static contrast ratio between 700:1 - 1500:1. As for a 4K TV, we can assume the ratio of Grundig 65GGU7900B to be on the upper side, that is atleast 1200:1.
HDR and HLG (Hybrid Log Gamma) are also supported on this TV.
As for brightness, the peak luminance it can achieve is 250 nits, powered by Direct LED backlight.
Gaming Performance
If you are planning to use your TV solely for content consumption, you can ignore these specs. But if you are also going to use the TV for gaming or use it as a PC monitor, you would want to take a TV that features the lowest input lag and response time.
Unfortunately, Grundig did not specify the input lag on this unit. But as this is not a cheap TV from Grundig, input lag on this TV could be 20ms or below.
Understanding Input lag and response time
This lag is the amount of time at which your device inputs changes the content of the screen. Though, this won't matter much if you aren't into competitive/FPS games like call of duty.
For best of both worlds, get a TV that features an input lag and response time of < 20ms.
Ergonomics and Dimensions
Now, coming to ergonomics — a VESA mount with interface size of 400 x 400 mm is provided for wall-mounting. There is no Swivel, Tilt or Pivot feature support in this TV.
Vertically, the TV measures 65 inches and horizontally 57.75 inches. In total, it weighs around 17.5 KGs.
Hardware and Audio
The TV comes with a Quad Core CPU. There is no mention about the total available RAM on the TV's official specsheet.
The UI on this TV is powered by Android TV Operating System.
For display connectivity, there are three HDMI 2.0 ports on this TV.
For connecting USB devices, it includes two USB 2.0 ports. Other connectivity ports include — 1x Satellite In (F-type), 1x CI+ 1.3 and 1x Ethernet RJ45.
Wireless connectivity options on the Grundig 65GGU7900B include Wi-Fi (2.5Ghz) and Bluetooth.
Coming to audio, Grundig has provided 2 x 10W built-in speakers on the TV.
As for power consumption, on average, it uses 114.24 watts and on standby, it takes 0.45 watts.
For powering this unit, you will need either a 110V or 220V outlet @ 50Hz-60Hz.