new laptop advice wrt PS

I have the same cpu with the 140T iGPU and it doesn't work on my Asus Laptop with 64 GByte RAM (used as VRAM by the CPU and GPU).
Unfortunately, Denoise in ACR 17.3 always crashes after 20 seconds when I try to denoise 45 MPixel images.
For some reason, it ran through once a few days ago, so it works in principle. Unfortunately, it crashes reproducibly after 20 seconds as a rule.
I have tried a lot of different thinks - new Intel firmeware, max Speed in Windows and ASUS Mainboard and so on. But it doesnt't work.

It looks like the Yoga Book you are proposing only has the integrated graphics that come with its Intel Core Ultra 7 255H processor? That would probably be Intel Arc graphics. I don’t know exactly how fast Intel Arc graphics can run Denoise on a 20MP image, but there have been reports about an incompatibility that caused Denoise to take too long. The links below about that problem are from 2023 and 2024, so I do not know if that has been fixed by now. You would need to find out.

Photoshop/Lightroom Denoise AI doesn't work with Arc cards (Intel forum)

Denoise takes over 40 minutes to process one image (Adobe Community)

If you took D Fosse’s advice to get a laptop with a discrete Nvidia GPU of the 3xxx/4xxx series, Denoise would be well under 1 minute per image, probably under 20-30 seconds.

b. will its Integrated Graphics work with Photoshop until, say, 2030?
(no one knows for sure, but...new AI functions will arise now to 2030?)

By @Jeffrey Greenberg

It will probably work, but might be a lot less satisfying 6 years later. Just as today, the integrated graphics from 6 years ago might work but are too slow to be useful. No one can guarantee what will work well in 2030.

could vastly speed up my GPT-4o + Adobe Bridge Description field keywording workflow

By @Jeffrey Greenberg

If you mean how quickly you can view image after image while entering the Description, that depends on whether image previews are immediately ready in Bridge, and if not, how quickly an image preview can be rendered. Yes, a new laptop should be much faster than the old one because the CPU and GPU are faster, but for it to work best, pay attention to the preview rendering settings in Bridge and configure them properly.

is an option to also buy external Dedicated Graphics box for this laptop with Integrated Graphics?

By @Jeffrey Greenberg

Currently, there are two options for an external discrete GPU:

• Thunderbolt. This is possible if the laptop has a port that supports Thunderbolt 3 or later. 
• Oculink. This is a newer option that requires an Oculink port. Because Oculink is realtively new, an Oculink port is much rarer than Thunderbolt at this time. Oculink gets around some of the limitations of Thunderbolt. 

Adobe does not seem to make eGPU compatibility a priority, so it can be difficult to know whether an eGPU will be compatible. I don’t even know how well the new Oculink eGPUs work with Adobe apps. Also, most eGPUs are not mobile because they require AC power. And the cost is high, when you add up the cost of the graphics card, the cost of the eGPU enclosure, and the cost of a 40Gb/sec Thunderbolt cable long enough to be practical.

You’ll probably find it much easier, and maybe also cheaper, to get a laptop with a good discrete GPU in it instead of an eGPU.

Not recommended. It may work, but not well. You need more powerful graphics from the Nvidia RTX series.

Note that dual graphics is always a potential conflict. Again, it may work, and it may not. It depends entirely on how the manufacturer has configured the two GPUs. It may be necessary to completely disable the integrated GPU.

Photoshop uses the GPU for actual data processing, and the result returned to Photoshop for further processing. It's not a simple downstream flow, it goes both ways. You can't send data to one GPU and get it back from the other. There can only be one GPU in that equation.

Any Nvidia RTX model, at nominal specs and configuration, should denoise 20MP in 5 to 10 seconds.