You can get Pocket Multi Slide and or Pocket Lift and Slide doors but they may not be a whole lot less than folding doors.

A garage door would work. ;)

A 12' hole in your building envelope's insulation and air seal isn't the best from an energy efficiency or climate control standpoint. You must be in a very temperate climate like CA. If so, then the only solutions to your issue are pretty much the expensive ones. If you are some place with weather, then you need to reconsider the idea.

Hope you aren't in a bug-infested area, with flying things and critters who are attracted by light at night.

Those glazed folding exterior doors look great on the TV home shows, but they are in the 5-figure range and can be problematic in cold zones.

I assume they make screens for them. Wouldn't any type of door without a screen has the same problems with bugs?

You're the Falls Church modern house, right? Well, there are about a dozen days per year, mostly in October, when having the doors open to the outside are possible without it being too hot and humid or too cold and humid. The whole area is a swamp after all. You might also find a few days in late March before the April rains come that are open door worthy, but if you aren't careful then, the wind will rip the doors right off of the hinges. Had that happen to a neighbor.

There's no real good solution to screening out bugs for a 12' opening. At least none that are unobtrusive and really work for the giant bugs that VA has. And, no screen will keep out wildlife. There are more raccoons in an urban environment than there are in rural areas. They aren't at all shy either. And can open trash cans. And even some windows and doors. You haven't lived until you've chased off Rocky from inside your house for the third time that night! You learn to keep your doors SHUT and LATCHED.

Friend of ours put the moving wall in on 2 sides of his sun room/patio and is very happy with their energy efficiency and ease of use....but they are the $$$$ ones from Germany.

Do they still make the triple hung windows like they used in the south so you could open them up to be like doorways to the outside?

There are screens for Nanawalls, but the panels break up the opening in a wall that almost negates the reason you'd have the operable glass wall. In VA, such a wall could work better between a living room and a screened porch.

Some areas of the country don't have swamp bugs.
Some areas of the country aren't subject to tropical storms either. Nor, blizzards.
Those are the areas that lend themselves to full wall openings.
Do all of these apply to your area?

Is this like a traditional lanai-type thing? I'd look for a lanai door for inspiration.

If you have 3ft of extra wall on each side of the opening, you could have 4 panels of 3ft sliding door stacking 2 panels each side of the opening. That would be on 2 tracks.
If you only have one 3ft length wall on one side, then you could do 4 tracks.