Comment 21 for bug 168164

Inkscape uses a resolution of 90dpi for the "real-size"
representation. So, if you create a 90x90px square it will be 1x1
inches in "real" units.
A typographic point is 1/72 of an inch, which is equal to a resolution
of 72 dpi.
90/72=1.25. So 1.25 is the factor you can use to translate between
inkscape pixels and real-world typographic points.

I guess it's pretty trivial (and probably a horrible hack) to add a
unit selector in the text dialog to choose between points and pixels
using just that factor. Internally it would simply multiply or divide
the desired size by 1.25.
It doesn't sound like an elegant solution to solve the problem, even
for my non-programmer brain. But at least it would be a temporary fix
for an old bug that people who work in print production have been
asking for years.