With this enhancement SovleSpace would be able to link these files into an assembly. Linking is much simpler than importing (converting) into .slvs format and would be limited to much less than 64K verticies. These files contain triangle mesh data which would be used to create vertex entities and a mesh (solvespace mesh) which would be linked in as a new group.

I would recommend this as a task for someone that wants to get more involved in SolveSpace internals. If you can write your own parser for either of those formats you are probably capable of doing the integration with a few tips on what goes where.