Flare Nut for rare Unloader valve needed

[Motofixxer]

So it appears to be around an M10 flare. It's smaller than 1/4" flare but larger than 3/16" flare. The outside of threads measures 10.36mm.

It's an an ALL Power APC4005 Twin stack air compressor. I believe also sold under Sears, Lowes, Strikeforce and others somewhere around early 2000's or so. They don't sell compressors anymore and only a few random parts left from later models.

I need to add the unloader line from this valve up to the switch since it's not there anymore. I bought the thing for a whole $10...but guy didn't know much about it. Thought if ya put a cap on there it would fill. He stuck his finger over it and it started filling. The pressure switch end is a fairly common M10-1.0 inverted flare that I can work with.

The problem seems to be nobody has an M10 flare nut that would fit it. So looking for options that might work for it.

This is actually kind of a nice design unit with wheels and a moving handle. Otherwise it's nothing special but decent output at 4.2CFM @90