Yes and No.
An SVG can be imported as a background image that can de drawn over.
DXF files can not be Opened / Imported in Seamly2D.
VIT files are the old Valentina ext for SeamlyMe measurement (.smis) files. While SeamlyMe will still open vit files that may be deprecated at any point in the future. Like wise VAl files are the old Valentina ext for Seamly2D pattern (.sm2d) files.
FYI:
SM2D... Seamly2D pattern file. SMIS... SeamlyMe Individual Size measurement file. SMMS... SeamlyMe Multi Size measurement file.
That being said… it’s possible to import an image file and draft over it, bu I took a different approach to digitize existing (paper) patterns. It entails 1) knowing what size the existing pattern is so you can formulize it to resize. 2) Basic knowldge of grading to know what grade points to include and how much they move up/dn lt/rt when grading 3) Drafting each grade point by locating it’s x:y pos from a given origin point. I did an example years back on digitizing a basic shift dress an employee of mine draped… you can find it here: Shift Dress Pattern