Not sure what you want from us . I find teens for sure usually study in the bedroom regardless of how much parents think this idea works. Why not a nice spot for you to read a book or listen to music instead. I think if you are concerend about what the kids are doing on the computer then the kitchen is the best place for homework to me this would be just like their bedroom not really visible for you to watch

Because of the size and configuration am not sure you could accommodate much more than a chair and perhaps a sidetable.

Generally in these poorly planned (by the builder/architect ) spaces we like to do floor to ceiling built in book shelves on your wall labeled 103. Depth wise there isn't really room for much else. Then a chair in the corner and depending of how you will use it an ottamen and small drink table.

I am assuming the area labled 164 is open raiing to below?

If you really need a desk like situation for your kids, which think long and hard if they would use it because 9/10 the answer is no, then you could have a finish carpenter come in and buld a shallow desk on your 103 wall and place two desk chairs there.

if you don't want to invest in custom then a parsons table would be a shallow option to use as a desk. Because they have flat sides you can butt them up against each other to create one long area

Then do a couple of parsons chairs in fabric to bring some interest to the area.

Lively art work above the consoles on that wall.