This is quite soft. Even for livebearers that do well in soft water. I already gave you some options which thrive well in soft water but preferably from 4 - 8 dGH 70 - 140 ppm soft and up.3 dgh/60 tds
As already mentioned by Gary is that you could join and/or inform at the ALA if they can help you out. Maybe one of the members of the ALA may have the suitable livebearers you're seeking for.
You really don't have to try an lfs. They won't have them.