We did this

Two bifold doors.

It’s not just the meter. We were told we need the piping accessible as well. There’s no “door frame”. Just framing that was put up for the dry wall.

You have to install a door frame and a door, sized to fit. What are your options? You could hang a curtain. But the logical solution is a door. So it follows, you need to install a door frame. Simple.

Does a single bifold door need a door frame?

Yes

This isn't a big deal. You need 4 or 5 studs, a prehung door, a passage door knob set, some patching/painting of drywall, and a threshold.

I wouldn't even put on a door knob. Have magnets to hold door closed. Paint a simple door the same color as the walls. Some plain unfinished cabinet doors from a big box store or even some close out left over doors they no longer stock. A good handyman can figure out something/ somehow to attach them. It's not like they will be something that needs to be used often.

I don’t want them exposed but there is a turn off on one of the pipes. Gas company said in an emergency, we need to be able to access it.

The best solution is a set of doors to look like a wardrobe as many sugested above.

Until you figure out how to frame the opening for that purpose you can just hang a simple curtain rod and opaque curtain

Most likely scenario is the utility owns the piping up to the meter - that needs to be accessible, including any regulators or shutoffs in and around there. After the meter you can obviously enclose your piping. Just put a full size door to match the one down on the left, it doesn't change any of the usage of what was happening in front of this bumpout anyway.