i’ve used the nucs for some openframeworks installs that have done basically what you are doing. I have used a zotac for an install using unreal.
i haven’t had any problems with either. I also haven’t run TD on either.
If i was looking to run TD on one of them, i would probably go with the zotac since they have their own nvidia cards.
We primarily use NUCs if we need a low cost computer. Mainly the 7th and 8th generations. Any of them will run TouchDesigner but of course you’ll be able to do a lot more with the i7 versions. They also have a version without the enclosure if you’d like to build your own.
If you need a GTX card it seems like the ZOTAC computers are a pretty decent choice. I don’t have much experience with them but I’ve heard good things.
Another thing you might consider is building a machine with a mini-atx motherboard. Then you could get a full size graphics card and maybe even a capture card. This case is pretty decent for that: