Sumatra PDF is a PDF, ePub, MOBI, CHM, XPS, DjVu, CBZ, CBR reader for Windows

How to fill PDF forms offline?

For one way to fill Forms using MuPDF-GL see above.

SumatraPDF has basic annotation which is in development but will be compatible with those in MuPDF-GL which allows for more types currently. See https://forum.sumatrapdfreader.org/t/highlighting-text/2093 and [Fixed] Highlighting problem in prerelease version.